Reality Quest: Review of the AudioWise OPTO•DX (and how clean power makes everything better)

With the broad availability of mScaler with the Chord Hugo mScaler, some wonderful products are coming available to really showcase the revolutionary impact of mScaler. In the early days, us Chord Blu2 owners were limited to DIY options and experimentation. Today, not only does Hugo mScaler have improved RF suppression (vs Blu2), but there are now several very credible commercial options for having a turnkey high-hygiene DX dual BNC connection between mScaler and your Chord DAC of choice.

The latest is something I’ve been waiting for for a long time: the OPTO•DX from AudioWise (https://audiowise-canada.myshopify.com). Unlike other options that focus on filtering to minimize RF on BNC cables, the OPTO•DX goes right to what I always thought would be the end game: true optical and electrical isolation between mScaler and your DAC.

Dan (@dmance) was kind enough to reach out and provide me with one of the first prototype units for testing, with the ask that I give feedback into development (which was a lot of fun), and that I share my unbiased and independent impressions with the community once the unit is ready to ship (which I am delighted to do).

In the interest of disclosure, I have no commercial relationship with Dan, and am sharing impressions as an audiophile without any commercial conflict or bias or economic benefit to me. I have only recently finished running through my full test matrix with a final preproduction unit (Dan tells me these preproduction units are identical to the production units he’s going to launch with). At long last Dan is ready to publicly disclose the product, so I’m finally able to publicly share my experiences with it.

Since this is fundamentally a new approach to one of the most critical links for anyone with a mScaler, I put it through the full battery of tests and configurations, and learned a heck of a lot along the way. Because of the criticality of clean power to digital hygiene, I also took a long and winding and very productive detour into DC power hygiene and AC power hygiene.

Please forgive the long write up, but having gone through all this, I’m convinced that the various test scenarios are interesting not just to determine if something may be useful to others, but also because they give insight to what factors can impact the remarkable quality of mScaled music, and what knobs are available to tune them up.

For those that care less about the method than the results, I have included a TL;DR findings summary at the end of each section, and I have rolled up my interpretation of my findings at the very end. I also have my current recipe (based on my findings) summarized there.


Background on Digital Hygiene

I know that digital hygiene in audio can be a contentious topic (bits are bits, right?). Rather than debate mechanics, I am sharing my experiences in my home with my equipment with my ears and my biases. Almost certainly yours will vary. Hopefully my experiences are helpful to you, but it not, that’s OK too. As a disclaimer, I’m a hobbyist not an expert. I am sharing my experiences and learnings as I try to figure things out, and I am eager to hear the experiences of fellow travelers. If something below is of potential interest to you, give it a go, and let us know what you hear and learn!

My efforts in digital hygiene have been driven by the following core principle: any digital hygiene optimization must start and end with your DAC. If it doesn’t somehow someway impact your DAC (even if you have no idea how or why), it won’t impact sound quality. If one is starting with bit-perfect sources (and if you’re not, fix that), these bit-perfect bits are not affected at all by any digital optimizations (if bits were being changed, you would hear very audible pops clicks and drop outs).

For me, the core question for digital hygiene and optimization is how to best preserve the clock, ground, and reference power of the DAC? Put another way, what can be done to the digital chain to minimize anything being injected to or induced in the DAC that impacts clock, ground, or reference power in the DAC?

I’ve be surprised again and again in this journey, but for bit perfect digital audio streams, I have to take as ground truth that unless something on the digital side is impacting clock, ground, or reference voltage in your DAC, you are not going to hear it. The impact may be direct, or it may be indirect through several intermediate components, over wires, or over through the air. If you hear a difference with bit perfect audio streams, something is be transmitted to or induced in your DAC that is impacting the core references: clock, ground, reference voltage.

Couple rules of thumb that I try to apply when thinking about this stuff:

• Anything in your chain impacts everything downstream (what it is plugged into), and anything in your chain (annoyingly) impacts everything upstream (what plugs into it). It can also impact things through the air (WiFi base station broadcasting 2.4GHz), and be impacted from the air. Some of these impacts don’t matter at all, some matter a lot. Study and understand all these potential vectors in and out of your DAC, and decide which ones you want to test and attack or eliminate.

• Everything in your chain has internal goodies that can be impacted by nasties, and these internal goodies can induce nasties that impact itself and other pieces of kit (there is a reason the mScaler is a separate box from the Chord DACs...the FPGA is a beast of a processor). Study and understand these potential sources and sinks, and decide which ones you want to test and attack or eliminate.

• Draw a diagram of your setup, with all the wires in and out (mine is at the end of this review). If anything has a metal path to your DAC (even through your home electrical wiring) pay attention and think how crap through that connection could impact your DAC. If anything is a power line, think about how power levels bouncing around or power noise could impact your DAC. Once you start sleuthing, you’ll be surprised how audible things are, how nasties can hop through many steps to impact your DAC, and how insidious noise can be.

• The thing with RFI and high end audio is that what works and what doesn't work is INCREDIBLY situation dependent: your home setup, what else is happening in your house and neighborhood, what equipment is on or off, etc. Just because something works (or doesn’t work) for someone else doesn’t mean it will work (or not work) for you. All these reports and experience are tactics on the tool belt, not a recipe to win a battle. My recommendation is when you read about experiences with shielded cables or ferrites or power supplies or anything else, take it as input for things to try and see if it matters in your setup. If you don't hear a difference, fantastic! If you do, even better still.

Am I confident that if you were in my living room as I did these experiments you would hear the same? Absolutely, because several of us were there when we did some of these tests and we all heard very similar things.

Am I confident if you buy the same cables and ferrites and power supplies and everything I did, that you'd hear the same thing I hear in your setup? Not at all! Your RFI world is potentially WAY different than mine.

Am I confident you’d consider what you hear significant or important or worthwhile? Not at all, we all have different expectations and sensitivities to sound, with different thresholds for what something is worth to us and how much expense and hassle we are willing to put up with to get it.

Paradoxically, every time you step up the performance ladder (better DAC, better speakers, etc), it is easier and easier to hear things that are dragging performance down. The fantastic news is that with the incredible performance of the Chord stack, you have world class equipment that is refined enough to easily hear these differences.

Enough blather…let’s get to the OPTO•DX, and take a trip into the digital hygiene rabbit hole.


So Tell Me About the OPTO•DX

The OPTO•DX takes dual BNC in from the Hugo mScaler on the “dirty” side (the TX unit). It converts that dual BNC signal to optical signals, and then has dual fiber optic outputs that connect the TX unit to a second independently powered unit on the “clean” side (the RX unit). The RX unit then converts the optical signal back to electrical, and connects to your Chord DAC (Chord DAVE in my case) via dual BNC cables. Each of the units is independently powered by external 12V supplies, and in separate boxes to minimize capacitive coupling between the “dirty” and “clean” sides.

Essentially, the units together give you true 100% optical isolation between your mScaler and DAC, with independent power for the “dirty” and “clean” sides. In effect, it creates both a signal and electrical air gap between everything upstream of the DAC and the DAC, in theory providing the ultimate in digital hygiene at the most critical stage immediately before your DAC.

In my setup, I connect my Hugo mScaler to the dirty side (TX), and connect the clean side (RX) to my DAVE, which I then use to directly drive my high efficiency Voxativ 9.87 speakers.

When evaluating the OPTO•DX, I tested it with a variety of switching 12V supplies, batteries, and advanced linear supplies on both sides of the OPTO•DX. I also experimented with different DC cables, and with a variety of BNC cable configurations (stock, ferrited, etc) on both the dirty and clean sides.

Once I settled on an optimal configuration between the HMS and DAVE, I then went back and removed some of the digital tweaks that I’ve been experimenting for these past several months. The question I wanted to answer is whether the OPTO•DX could basically eliminate the need for upstream digital tweaks and optimizations, by cleaning up the signals right before the DAVE. That is, how well does the OPTO•DX deliver on our ultimate dream of a single digital “moat” that takes care of everything, so we can get rid of all the upstream digital and power crap.

I was very very excited to test the OPTO•DX in my system. With this configuration, it is in theory possible to basically isolate my DAC (Chord DAVE) from all upstream electrical and RF noise, and isolate the DAVE electrically by connecting it (and the clean side of the OPTO•DX) to a dedicated power circuit with isolation transformer, etc. In theory, we’re getting to ultimate hygiene levels. But how does theory map to real listening experiences?

TL;DR - Pretty damn well!

To test the theory, I explored basically three different areas to see what impact the OPTO•DX has, and how best to configure it. They are (from most obvious to most esoteric):

• Different combinations of BNC cables
  • Stock Chord BNC cables vs my DIY ferrited cable of shame (FCoS) that I describe in great detail in my long Blu2 review (https://www.head-fi.org/showcase/chord-blu-mk-ii-digital-cd-transport.22848/reviews#review-19675)
• Different power supplies and DC cables to the clean and dirty side of the OPTO•DX
  • Stock switching supplies, AA batteries, laptop batteries, precision linear supplies, etc.
• Whether other digital tweaks upstream of HMS were still needed
  • USB regenerators, optimized NUC end points, cables, etc.

I’ll start with BNC cables, since that is what you’re buying an OPTO•DX to replace.


DX Optimization - Baseline

For the baseline, I started with Hugo mScaler -> Stock Chord BNC -> DAVE vs HMS -> FCoS -> DAVE, to repeat the experiment I did with Blu2 and DAVE in my big Blu2 review (see my Blu2 review for specifics on the BNC cables and ferrites in my Ferrited Cable of Shame, what I heard, music I use for critical listening, etc)

As I’ve reported previously, even with Hugo mScaler, there is (to my mind) a significant SQ lift when using the FCoS, although it is much less of a lift than I remember when I had my Blu2. I confirmed this difference is still there with my current optimized digital chain (it is), and used this as my sound quality baseline.

TL;DR - Even with Hugo mScaler, I hear a clear and welcome sound quality improvement when using heavily ferrited BNC cables (but less of a lift than I remembering hearing with Chord Blu2)


DX Optimization - Ferrites vs OPTO•DX

Next, I inserted OPTO•DX into the chain, but with generic switching power supplies on each of the clean and dirty sides (optical isolation, but no power hygiene). I used stock Chord BNC cables to connect the Hugo mScaler to the OPTO•DX dirty side, and stock Chord BNC cables to connect the OPTO•DX clean side to my DAVE.

Compared with FCoS going from HMS direct to DAVE, OPTO•DX with stock cables and stock SMPS power had a clear and unambiguous sound quality lift (all the stuff we’ve come to expect as you clean up RF with ferrites, just more of it). This was a pleasant surprise, and gave me hope that I could finally part with my FCoS!

Next, I swapped in my FCoS on the clean side of OPTO•DX to connect to my DAVE, and compared to the stock Chord BNC cables from clean side of OPTO•DX to DAVE. Essentially, was anything still getting through the OPTO•DX that the ferrites would clean up? In this configuration, I gave a very slight edge (mainly in depth queues) to using the OPTO•DX with the FCoS. (Unfortunately) There is still some residual something that the FCoS is cleaning up, but there is more to that story…

TL;DR - OPTO•DX out of the box is a clear step up from heavily ferrited BNC cables, but the combination of stock OPTO•DX and heavily ferrited BNC cables is better still.


Sidebar - DC Power Quality Is Surprisingly Important For Digital Audio

All of the above experiments were with stock 12V SMPS’s, with stock DC cables. I have been finding that quality DC power can have a huge impact with digital audio, so my next step was to explore the sensitivity of the OPTO•DX to DC power quality, and to see whether the OPTO•DX reduced or eliminated the impact oF DC power upstream in the digital chain.

As background, I have on order a custom Paul Hynes SR7 DC power supply with three dual regulated DC rails. This promises to be the ultimate audiophile DC supply, but it could be years before Paul gets around to building mine. As I’m waiting, I have been experimenting with various DC power configurations to see what improvements I can have while I wait, and to learn more about the impact of DC power supply quality on sound quality.

Currently, I have on hand stock 12V SMPS’s, a couple PowerAdd Pilot2 portable laptop batteries with variable DC output (https://smile.amazon.com/gp/product/B015OAJFOC), a couple Uptone Audio UltraCap LPS 1.2 linear power supplies (https://uptoneaudio.com/products/ultracap-lps-1-2), and several AA battery packs (https://smile.amazon.com/gp/product/B01GEBW7Q8).

Having the assortment has been invaluable in tracking down power and noise issues because they each emphasize a different aspect of power quality. By narrowing down sound quality differences between these different types of power sources, it shines a light on what aspects of power quality seem to have the largest impact. These key differences are:

• The AA battery packs have perfect electrical isolation and no switching noise, but terrible voltage regulation (pro tip: you can adjust voltage output with AA battery packs by adding and removing AA batteries, and using a paper clip to jumper to the output terminal)

• The PowerAdd Pilots have good electrical isolation minimal switching noise (it is fully disconnected from main, but has internal electronics), and good but not great voltage regulation

• The Uptone LPS 1.2 has great isolation (it has a unique internal battery switching mechanism so it is always disconnected from mains), and fantastic voltage regulation if you operate away from its max current limits

Swapping these supplies into different parts of my chain, it is very easy to hear differences and learn what aspect of power makes the most difference for any particular component.

I generally have found the AA battery packs great for helping understand where mains noise may be impacting your system, but I have also found that quality voltage regulation (and related to that, dynamic current capacity) has a huge impact on digital equipment, and that these AA packs just don’t cut it. I generally use the AA battery packs more for quick and dirty diagnostics (which they are awesome for), and don’t use them for critical listening tests. As I step through the tests outlined below, I am using combinations of standard switching power supplies, the PowerAdd Pilot2 batteries, and the Uptone LPS 1.2 supplies.

TL;DR - DC power supply quality really really matters. Having a variety of supplies available is really helpful to identify what aspect of power supply quality (mains isolation, voltage stability, low noise, etc.) is most impactful at different parts of your audio chain.


OPTO•DX Optimization - What impact Does DC Power Quality Have On The OPTO•DX?

My first set of power experiments were test stock SMPS vs PowerAdd Pilot2 vs Uptone LPS 1.2 connected to the “clean” side of the OPTO•DX (the side closest to the DAC). During these tests, I used a stock SMPS on the OPTO•DX “dirty” side (the side closest to the Hugo mScaler). I heard a big step up in sound quality with the PowerAdd Pilot2 over SMPS, and an even bigger step up with the LPS 1.2. The clean side of the OPTO•DX really benefits from cleaner/better power.

Next, with an LPS 1.2 on the clean side, how does power quality to the dirty side of the OPTO•DX impact sound quality? Powering the “dirty” side with a PowerAdd Pilot2 gave me a nice SQ lift over SMPS on the “dirty” side (again, “better” being all the things we hear as we clean up RF on the BNC lines…better depth and height imaging, more detail, etc). Better power to the dirty side matters, implying that power may be introducing some signal modulation that traverses the fiber link to the clean side.

I strongly suspect 2 LPS 1.2’s (one each for the dirty and clean sides) will be another step up, but I don’t have a spare LPS 1.2 to experiment with this configuration right now. I have a Paul Hynes SR4 on order, and when that arrives, I’ll be able to bring my 2nd LPS 1.2 to the OPTO•DX party and verify one way or the other.

Regardless, it is clear that clean stable power makes a big difference with the OPPO•DX. If your budget allows, I highly recommend that you at least audition a LPS 1.2 in your setup (@Superdad has a VERY generous 30 day no questions asked return policy)

TL;DR - The Uptone Audio LPS 1.2 is a great addition to the OPTO•DX, and you should definitely audition it (or something similar) to see what it does for you. Improved DC power has a significant impact on the “clean” downstream side of OPTO•DX, and a lesser but still very welcome impact on the “dirty” upstream side of the OPTO•DX. For the OPTO•DX quality voltage regulation seems to be more important than mains isolation.


OPTO•DX Optimization - What impact Do Shielded DC Cables Have?

So the above tests were stock DC cables. Is there a benefit to using short shielded DC cables with high quality conductors and connectors? To test, I left the PowerAdd Pilot2 on the dirty side, and switched the DC cable from the LPS 1.2 to the clean side to a Ghent Audio DC-GAC4 Gotham GAC-4 shielded DC cable (https://ghentaudio.com/part/dc-gac4.html).

With the Ghent DC cable, I heard a VERY nice lift (this was surprising). I had heard from people I trust that DC cables can have a big impact, but this was my first test of that since I had received my Ghent cables. Color me impressed!

I then switched to my fancy new Ghent Custom Neotech 7N 18awg DC splitter-cable (also JSSG360 shielded) to feed both the clean and dirty sides of the OPTO•DX from the same LPS 1.2. In this configuration, the sound was perhaps a big darker than the PowerAdd Pilot2 to the dirty side and LPS 1.2 to the clean side. I had to go back and forth a couple times, but I currently prefer the same LPS 1.2 feeding both units with the Ghent shielded splitter cable.

I’m very much a novice at this DC cable stuff, just starting down this particular corner of the rabbit hole. It is unclear to me whether the DC cable shielding is more impactful, or the quality of the conductors, or the connectors, or some combination of all the above. Sounds great though, so doing a future deep dive into DC cables is now on the “to test” list.

TL;DR - A quality well shielded DC cable has a surprisingly positive impact on sound quality. If you only have one high quality DC supply, get a splitter and power both sides of the OPTO•DX with same quality power supply and the same quality DC cable (the lift from quality voltage regulation to both sides is more than the loss from any leakage path between the sides).


With OPTO•DX + Clean Power, Do Ferrites Matter Any More?

As a next test, I took my optimum power configuration (LPS 1.2 feeding both dirty and clean sides of the OPTO•DX, using the Ghent DC splitter cable), and experimented with the stock Chord BNC cable vs FCoS from the clean side to the DAVE. With clean power to the OPTO•DX, is there anything left for the ferrites on the FCoS to filter out?

If there was a difference, it was very very very slight (I can’t say there was). Once you have solid power sources for the OPTO•DX, it looks like there is nothing left to clean up! (at least anything that I can hear) I may finally be able to retire the FCoS!

TL;DR - With clean power to the OPTO•DX, I no longer hear a benefit with a heavily ferrited BNC cables vs the stock Chord BNC cables. My Ferrited Cable of Shame is now retired!


With the OPTO•DX, Do Upstream Tweaks Still Make A Difference?

Now it’s time for an extended detour in the wild and wooly realm of digital tweaks and optimization. The question for me is if one has “ideal” signal isolation going into the DAC, do any of the upstream digital tweaks and optimizations that I’ve accumulated over the years still matter? They all mattered quite a bit when I first put them into place, but are they obsoleted by the OPTO•DX?

Beware, here is where the true dragons dwell, with lots and lots of different ways to poke the dragons. Look to the summary at the end of each section if it gets too wooly.

As a baseline, I currently run the following for the rest of my digital chain:

• Roon server on a highly optimized NUC server - real time OS (Audio Linux), everything running in memory, real time priority and dedicated CPUs to the audio processes, ethernet bridged to a NUC end point to isolate ethernet traffic, etc.

• Roon bridge on a highly optimized NUC end point - real time stripped to the minimum OS, everything in memory, real time priority to USB interface and audio processes, fanless case, etc.

• Lush^2 shielded USB cable (JSSG360 shielded)

• Two Uptone Audio ISO REGEN USB regenerators in series (https://uptoneaudio.com/products/iso-regen), connected by Uptone Audio USPCB USB boards to each other and my Hugo mScaler. Both ISO REGENs are powered by a Uptone Audio LPS 1.2 via a generic DC splitter cable, fed by Ghent GAC4 shielded DC cable (alas, I only have one high quality shielded splitter DC cable, and I found it has a bigger impact on the OPTO•DX).

All of the below tests are with the OPTO•DX in an optimal (for me) configuration: powered by a common LPS 1.2, with the custom Ghent shielded splitter DC cable, using stock BNC cables, between my Chord Hugo mScaler and Chord DAVE DAC. With the OPTO•DX in place, I revisited each tweak, and explored if the tweak was still beneficial, and if so, if and how I could optimize it further.


Impact of USB Signal Integrity/Signal Regeneration

Previously, I had done a lot of experiments with large buffer processes on the NUC end point (using Squeezelite). Squeezelite is configurable enough to let me have maximum network caching (songs preload to memory in a second or so) and maximum in memory buffers between the end point process and the USB output.

This had a huge positive impact on SQ vs stock Roon Bridge (which has minimal buffering), but is extremely glitchy in practice (lots of song skipping, and playback freezes when Roon core gets confused dealing with the large buffers). Even though large buffer Squeezelite drives me nuts, the large buffers configuration highlighted the SQ that was possible, so a lot of my digital tweaking has been toward getting to that reference sound quality level without Roon getting all glitchy and skippy.

First, the Lush^2 shielded USB cable had a very positive impact, but there was still a long way to go to close the SQ gap between Roon Bridge and large buffer Squeezelite. With the Lush^2 in place, I next pivoted to USB isolation and signal regeneration to see if it was possible to get the SQ benefit of large buffer Squeezelite with Roon Bridge by cleaning up the USB signal before it got to the Hugo mScaler.

To experiment with this, I purchased an Uptone Audio ISO REGEN to audition in my system, and by chance got a second one to audition as well. When I added one ISO REGEN (with clean power from an LPS 1.2), sound quality improved quite a bit, but there was still a gap between Roon Bridge and large buffer Squeezelite.

When I added a second ISO REGEN in series (also with clean power from an LPS 1.2), the gap between Roon Bridge and large buffer Squeezelite virtually disappeared(!) Clearly cleaning up the USB signal going into HMS and injecting clean power into Hugo mScaler via the USB Vbus was cleaning up a lot of the upstream sins in my chain. I have been happily running this configuration as my normal listening configuration.

So with OPTO•DX in the chain, what happens if I remove the ISO REGEN’s and take USB direct from the NUC to the HMS? Is the OPTO•DX able to clean up whatever the ISO REGEN’s were cleaning up?

Alas, mostly yes, but not completely. I still prefer to have the ISO REGEN’s in the chain, but the gap is quite a bit less than what I was hearing before OPTO•DX. A very promising step forward, but there is still SQ to be revealed on the digital side of of the OPTO•DX moat.

If I didn’t have two ISO REGEN’s already, would I invest them to get this extra step up? Value (as always) is in the ear of the beholder, but I would be tempted, but it would be a tough call (who am I kidding, of course I would

TL;DR - Even with the OPTO•DX in place, USB isolation and regeneration still makes an audible improvement in sound quality, but the gap has significantly narrowed.


Impact of USB Vbus Isolation

So given the above, is the incremental benefit from the LPS 1.2 powered ISO REGENs more from the USB signal isolation and regeneration they provide, or from the ISO REGEN providing clean power on USB Vbus to the Hugo mScaler USB port, or both? Remember, Hugo mScaler uses USB Vbus to power part of its USB input circuitry. This means the USB input on Hugo mScaler is a power vector into HMS that you need to pay attention to. With the ISO REGEN, the LPS 1.2 is energizing the on board precision voltage regulators, which in turn are providing the Vbus +5V on the USB output of the ISO REGEN, providing very high quality Vbus +5V to the USB input to the Hugo mScaler.

To test whether USB signal regeneration or high quality Vbus is having a bigger impact with Hugo mScaler, on a lark (and with very little research) I bought a iFi Defender to test. This is a USB dongle which passes through USB signals, but has a separate micro USB interface on the side that can be used to inject external power into the USB cable (vs passing through Vbus and ground from the USB source).

For this experiment, I powered the iFi Defender with +5V from the PowerAdd Pilot2. This allowed me to inject clean power into the Vbus of the HMS directly (NUC End point to iFi Defender w/ PowerAdd Pilot2 to Lush^2 USB cable to HMS) with no ISO REGENs in the chain.

So how does it sound compared to have two LPS 1.2 powered ISO REGEN’s in series? The 2x LPS 1.2 powered ISO REGEN’s in series win hands down. Signal regeneration still matters.

Although it is a harder test to do with a single LPS 1.2 (to switch between configurations I need to switch the voltage on the LPS 1.2 from 7V to 5V), do things change when I powered the iFi Defender with +5V from the LPS 1.2?

First I compared the Lush^2 straight from my NUC to my Hugo mScaler, vs iFi Defender added to the Lush^2 (no ISO REGEN) with PowerAdd Pilot2 @ 5V, vs iFi Defender with LPS 1.2 @ 5V. The iFi Defender powered by the LPS 1.2 is definitely a non-subtle step up from the iFi Defender powered by the PowerAdd Pilot 2 (both were clear step up from a direct USB connection from NUC to HMS). The Hugo mScaler definitely appreciates clean power on the USB Vbus.

So how does the iFi Defender + LPS 1.2 injecting clean power on the USB Vbus compare to 2x LPS 1.2 powered ISO REGEN’s in series injecting clean power on the USB Vbus and regenerating the USB signal twice? No question, there is additional lift with the ISO REGENs. Both USB signal integrity and clean power on the Vbus are having a positive impact on sound quality. When running Roon Bridge on my NUC, USB regeneration and isolation still matter (which is consistent with hearing such a profound difference between large buffer Squeezelite and Roon Bridge when connected directly to the Hugo mScaler…USB signal integrity is having some impact on HMS, although I can only guess as to what the mechanism may be)

So is the second ISO REGEN helping because of additional signal regeneration, or by injecting clean Vbus into the next ISO REGEN, or both? Can clean power on USB Vbus let me go down to a single ISO REGEN in my USB chain? Let’s test that by comparing two ISO REGEN’s in series, vs 1 ISO REGEN with clean PowerAdd Pilot2 power on the USB Vbus (from iFI Defender) input to the ISO REGEN, vs 1 LPS 1.2 powered ISO REGEN.

2 ISO REGEN’s (LPS 1.2 powered) in series still clearly have the best sound quality, followed by 1 ISO REGEN (LPS 1.2) with a clean powered iFi Defender (PowerAdd Pilot2), followed by a single ISO REGEN (LPS 1.2). The ISO REGEN clearly benefits from clean Vbus. With two ISO REGEN’s in series, the LPS 1.2 power to the first ISO REGEN is powering the high quality voltage regulators that are feeding high quality Vbus to the USB input circuitry of the 2nd ISO REGEN.

Alas, the 2 ISO REGEN’s in series are staying in my USB chain, at least until someone finds a way to get the sound quality benefit of large buffer Squeezelite with the usability and convenience of Roon Bridge (alas, I’m too locked in to Roon to give up my Roon Core server, even if it refuses to play nice with large buffer Squeezelite).

TL;DR - Power on the USB input to Hugo mScaler has an audible impact on sound quality. Paying attention here will help isolate your HMS from upstream components. USB signal integrity is somehow having an impact on sound quality.


Impact of Mains Isolation

So what if I power the Hugo mScaler with a PowerAdd Pilot2? That would eliminate any mains connection on the Hugo mScaler and OPTO•DX (remember, the Vbus on the USB input to the HMS is being powered from the ISO REGEN, with is being powered by a mains disconnected Uptone LPS 1.2). That would completely isolate DAVE as the one component with a mains connection.

First I compared powering the Hugo mScaler with the stock Hugo mScaler Chord switching supply (15V) vs the PowerAdd Pilot2 at 12V. In this configuration, I prefer the HMS stock switching supply (slightly better spatial resolution and depth resolution). However, when I switched the PowerAdd Pilot2 to 16V, I clearly preferred the PowerAdd Pilot2 @ 16V to the HMS stock supply.

These are surprising findings for me, and a reminder to always listen with an open mind. Higher voltage seems to matter to HMS, enough so that the added benefit of 15V with SMPS outweighed the benefit from mains isolation at 12V.

Alas, the LPS 1.2 does not have enough current output to drive the HMS, so I have to wait for my Paul Hynes SR4 later this summer (and someday a double regulated rail on my Paul Hynes SR7) before I can properly test powering the HMS with a more serious linear power supply.

TL;DR - Clean isolated power to the Hugo mScaler makes a tangible difference in sound quality. You will need a higher capacity supply to properly feed the HMS, but I suspect sound quality will handsomely scale as you scale power supplies.


Impact of End Point Isolation (Optical)

Let’s keep marching back the digital chain. My end point is a NUC7i7DNKE in a fanless Akasa Plato X7D case, with 16GB of memory, and an Intel Optane M.2 2280 16GB PCI-e 3.0 x2 NVMe Memory Module where I keep boot image. I boot and run AudioLinux to memory, with a highly stripped down OS. That keeps power consumption low enough that I can actually run the NUC off of a PowerAdd Pilot2 battery or LPS 1.2(!). That will take mains isolation all the way back to the ethernet port on the NUC.

My NUC also has HDMI out. Using a Kanex HDMI Digital Audio Extractor, I can convert HDMI digital audio (up to 48kHz) to TOSLINK optical, and connect my NUC to the Hugo mScaler via TOSLINK. I have a lot of high resolution music content, so this is less than optimal for me, but it is a useful experiment to compare optical input with a battery powered HMS (complete electrical isolation) to my more typical USB to ISO REGEN (x2) path with a battery powered HMS.

Essentially, the experiment with the Kanex HDMI optical configuration let’s me assess how material is any crap that is getting into the HMS via the USB interface, and is it worthwhile to scrub that interface even more?

So in this experiment, I have HDMI out of the NUC going to a PowerAdd Pilot2 powered Kanex HDMI digital audio extractor, which is then connected by TOSLINK to a PowerAdd Pilot2 powered (16V) Hugo mScaler. I also have USB out from the NUC going through a shielded Lush^2 cable to 2x Uptone ISO REGEN’s in series (powered by +7V from a LPS 1.2 with Ghent Audio DC shielded splitter cable) going to the USB input on the HMS. On Roon, I am playing to both the optical and USB interfaces NUC as a grouped zone, so it is very easy to switch between the inputs on the HMS.

So with USB and optical connected at same time, I find it very difficult to hear a difference, but I give the slight edge to USB.

But crap could be getting through the USB interface and impacting optical playback. How does optical sound when I physically disconnect USB? When I physically disconnect the USB cable from the HMS, it is very easy to tell difference between optical and USB. With optical, I’m hearing more of the usual benefit when RF is managed down (sense of space, clarity of notes), but something seems a bit off that I can’t put my finger on (vs USB). Perhaps too forward? More stress or less control while I listen? Even though optical by itself has more of I’m looking for in these digital hygiene experiments, I find myself preferring to listen to USB.

So all this was with the Kanex powered by +5V from the PowerAdd Pilot2. What happens with different power sources to the Kanex? With a stock 5V SMPS, the Kanex (vs the PowerAdd Pilot2) has a comparatively dulled and flattened soundstage. Once again, power is making a difference with an optical transducer.

The big revelation is when I compare the Kanex with PowerAdd Pilot2 vs Kanex with Uptone LPS 1.2 (5V). With the LPS 1.2, the impact is significant and immediate. That stress and awkwardness I’m was hearing with optical before is gone. Spatial resolution has gone up again, and almost all of the stress is gone. This is now the best my system has ever sounded (at least with my 44/16 Redbook content). Clearly the lowly Kanex is benefiting from better power regulation!

So all these tests were with Redbook content. I’ve resisted going down the all optical path because of my high resolution content. Given the great sound quality of the LPS 1.2 powered Kanex (!), can I live with the limitations of optical? To assess, I tried some favorite 192/24 Chesky binaural content via USB vs isolated optical with USB disconnected (Roon automatically downsamples 192/24 content to 48kHz). Unfortunately, I still prefer USB. I also evaluated some favorite Sound Liaison single mic 352/24 content (again, automatically downsampled by Roon to 48kHz). I again clearly preferred USB. To confirm that my hearing hadn’t drifted, I went back to some favorite Redbook content (no downsampling by Roon Core), and again preferred isolated optical.

Ug. I most definitely do not want different digital chains depending on what music I want to listen to. I need to do some research and figure out if there is LinuxFu to configure the HDMI output of my NUC to max out at 96/24 or even 192/24, and repeat these experiments. That is a project for another day.

TL;DR - It is easier to get to high quality sound with the optical inputs to the Hugo mScaler (if you can live with lower resolution content), but there are different gremlins with optical (vs USB) that I can hear but don’t yet understand. Even for optical sources, power stability seems to matter. There is more to explore here.


Impact of End Point Isolation (Power)

So with the rest of the downstream chain in an optimal configuration (OPTO•DX with LPS 1.2, HMS on PowerAdd PIlot2, NUC outputting via HDMI to a LPS 1.2 powered Kanex with optical to HMS, 44/16 Redbook content so I don’t drive myself crazy), how does running my end point NUC with a PowerAdd Pilot2 at 19V compare with the stock SMPS at 19V?

This is actually a more difficult A/B test, since it takes about a minute for the end point NUC to boot up and load the OS to memory. However, after swapping back and forth a couple times, I’d give a very slight edge to the PowerAdd Pilot2 (over the SMPS to the NUC). Mains isolation may be making a very slight impact on the NUC, but it is a VERY difficult difference for me to hear through the HDMI/Kanex/Optical path.

How about for the USB path? Does running the NUC off the PowerAdd Pilot2 battery close the gap between USB and isolated optical? Alas no. With the NUC powered by PowerAdd Pilot2, I heard approximately the same difference in sound quality between USB and optical with both plugged in (very slight), and approximately the same larger difference in favor fo the isolated HDMI/Kanex/LPS 1.2 path (with USB disconnected) over USB.

With all the other hygiene in the chain, I’m not hearing a material impact to power changes on the NUC. This is an interesting result for me. Several months ago, when I did some quick and dirty experiments with power on my NUC (prior to me adding all the other down stream optimizations), I did hear a clear improvement when using a PowerAdd Pilot2 to power the NUC. It is a reminder that every change one makes to the chain changes how everything else in the chain impacts sound quality (there are lots of different ways to filter out things that are adversely impacting the DAC).

TL;DR - Different power to my NUC didn’t seem to have a material impact (even though it had a noticeable impact before I had the OPTO•DX in the chain). As one optimizes different pieces of the chain, you need to go back and test previous learnings to see if they still apply.


How About A Purely Isolated End Point? (Network, Power, Optical)

I have (briefly) posted before about how impressed I am with the Chromecast Audio as a Roon end point (alas, it sucks serious backside as a Chromecast end point). It remains my go to recommendation for civilians looking to get to great sound quickly. For ~$40 used, you get a little puck of a device that connects to the network via WiFi (no crude coming down on ethernet lines), is externally powered so you can use clean power (clean power made a huge difference in my initial experiments several months ago), has TOSLINK audio out (up too 96/24 content with Roon with no downsampling), and Roon streams it bit perfect content and behaves impeccably with it. What’s not to like?

So how does CCA compare with isolated optical from the Kanex, with all the other optimizations still in place? (SMPS powered NUC, PowerAdd Pilot2 powered HMS, LPS 1.2 powered OPTO•DX, going to DAVE). In this case, HMS has 2 optical inputs, so it is very easy to toggle between the NUC + Kanex path and the Chromecast Audio path. (I should offer the caveat that while it is easy to switch between optical sources, my ear is still not used to optimizing an optical path…please forgive me for not quite being sure how to express the differences, or why I have a preference one way pro another…the differences are definitely different than what I’m accustomed to and I’m still getting my head around them)

So to start, how does the optimized NUC + LPS 1.2 powered Kanex HDMI path compare to the CCA powered by stock USB wall wart? With Redbook content, the Kanex HDMI path sounds smoother and more relaxed to my ear, with a more even (less sloppy?) tone. I easily prefer the LPS 1.2 powered Kanex to the stock Chromecast Audio.

When powering the Chromecast Audio with a PowerAdd Pilot 2 (5V), with Redbook content, the LPS 1.2 power Kanex is still noticeably smoother than the Chromecast Audio, but the gap has been reduced quite a bit. Switching to high res content, the PowerAdd Pilot2 powered Chroomecast Audio does an audibly better job with high res content (Roon downsamples to 96kHz with the CCA vs 48kHz with the NUC HDMI output) but still has stress compared to the LPS 1.2 powered Kanex. I still prefer the Kanex. This is making me that much more eager to figure out how to get my NUC to output 96/24 or even 192/24 to the HDMI output to the Kanex, so I can get the best of both worlds with high res content.

So how does the (very) lowly Chromecast Audio do as a Roon end point when powered by an Uptone LPS 1.2 at 5V, compared to the optimized NUC (SMPS @ 19V) + Kanex (LPS 1.2 at 5V) combo? CCA is very nice, but Redbook is still a bit more relaxed through the Kanex. Even with high res content, I still prefer the NUC+Kanex (even though the high resolution content is more detailed through the Chromecast Audio). I am suspecting that the output clock in the Kanex may be better than the output clock in the CCA? I’m going to need some additional components to audition to be able to triangulate what I’m hearing.

Regardless of the above, I stand by my recommendation that every Roon user should have a Chromecast Audio available as an optical end point into their Hugo mScaler. The quality per dollar ratio is completely off the charts, and it is a great baseline to have available as you experiment with with other end point options. Color me impressed that the CCA is able to scale to this level.

TL;DR - The Chromecast Audio is one of the best value Roon endpoints for the money you can get, and every mScaler owner should have one to experiment with. While better power definitely makes it better (way better actually), its performance ceiling is below what you can get with other approaches.


Impact of Network Isolation, Master Femto Clocks, Goosed Servers, etc (TBD)

VERY high on my list is to eval the Uptone Audio EtherRegen, when Alex (@Superdad) and team finally release it. That device promises to create a moat on the ethernet side going into the end point. If that moat is effective, I hope to be able to ignore everything upstream of the end point, and limit the part of my digital chain that I need to pay attention to to my end point and HMS (with the OPTO•DX providing the moat between HMS and DAVE). In theory, the stuff of digital hygiene dreams. Alas, EtherRegen is not available yet, and I have been resisting any investment in optimizing my network and server until it become available. Can’t wait to put EtherRegen (or similar network isolation solutions) to the test!

So how about fancy femto master clocks, goosed up servers, goosed up power cords and cables, etc? I have no idea. I’ve been intentionally avoiding all that stuff until the network isolation options shake out, and people with all these things already can report out on whether they still make a big difference.

Until then, I’m going to shift my attention back to the analog side (faster/better transducers, headphones, etc), and get back to my home theatre tinkering and see how I can easily integrate a high quality surround setup into this kit. No rest for the weary, but it will keep me busy (and distracted) until my Paul Hynes SR7 arrives, and I get to go through all this power stuff all over again.

TL;DR - There is a whole world of network hygiene, clock hygiene, server optimizations, mechanical isolation, and goodness knows what else. I am resisting diving into that end of the pool for now, but I am weak, and I will succumb at some point.


With A Newly Optimized Digital Chain, Does That Change Anything With The OPTO•DX?

Recall that at the start of this process, I did my evaluation of the OPTO•DX with my then preferred digital chain (NUC to USB through 2x ISO REGENs, Hugo mScaler on SMPS, etc). With the new chain (isolated optical via a LPS-powered Kanex HDMI link, Hugo mScaler on PowerAdd Pilot2 battery at 16V, etc), do my findings on how to optimally power and configure the OPTO•DX still hold?

First I started with comparing both the dirty and clean sides of the OPTO•DX with stock 12V SMPS’s, vs using a single Uptone LPS 1.2 supply with a Ghent Audio shielded splitter DC cable to power both dirty and clean sides. The LPS 1.2 clearly had better sound quality (enhanced soundstage, less stress, more natural, etc.) No surprises so far.

I then listened with the stock SMPS on the “dirty” side, and the LPS 1.2 connected with the Ghent Audio DC cable only to the “clean” side. To my surprise (and contrary to my findings when the Hugo mScaler was being powered by the Chord SMPS), the sound quality was a significant step up from the same LPS 1.2 powering both sides. Huh.

As a final test, I powered the “dirty” side with a PowerAdd Pilot2 battery at 12V, with the LPS 1.2 on the “clean” side. Another significant step up, and the best I’ve ever heard my system. I am now more convinced than every that a second LPS 1.2 to power the “dirty” side of OPTO•DX will be a very worthwhile thing to try.

Clearly, disconnecting the Hugo mScaler from mains (or removing the Chord SMPS) had a positive impact for me. In the new optimal configuration, I have an optical connection from my NUC to the HMS, HMS is running on battery (mains disconnected), “dirty” side of the OPTO•DX is on battery, and a mains disconnected Uptone LPS 1.2 is powering the “clean” side of the OPTO•DX. The DAVE is the last mains connected man standing, and it sounds glorious. But wait, that’s not quite true. As I’ll detail below, there is one more wrinkle to this story, but this time, on the analog side of the chain.

TL;DR - Always revisit your core findings and assumptions - when you change something upstream, what may be optimal downstream may change. In my case, disconnecting my Hugo mScaler from mains and SMPS by going to battery led to better sound by dedicating my LPS 1.2 to only the clean side of the OPTO•DX.


Are There Other DC Power Options?

Based on the urgent and consistent prodding of many audiophiles I know, I placed an order for a Paul Hynes SR7 several months go. My custom SR7 build will have three dual regulated (DR) rails, which basically is the ultimate DC supply. Based on my recent experiments with the LPS 1.2, this may turn out to be one of the better lifetime audio investment decisions I have made (Paul is no longer taking SR7 orders, but does offer spots in line when others cancel). Alas, the wait for my SR7 could be anywhere between 4 months (yeah right) and 4 years to never. It is a crap shoot if and when mine gets built.

In the meantime, besides the AA batteries, laptop batteries, and the awesome Uptone Audio LPS 1.2 that I have been experimenting with, are there other options available as well?

I currently have a Paul Hynes SR4 on order, just to get a sense of what that next level of supply will do in my system. It has more current output capacity than the LPS 1.2, so it will allow me to mix and match and experiment with more configurations. Uptone Audio has their own higher current capacity (and dual rail) JS-2 supply. Once I have my system (and ear) better tuned, I may track down a unit for a proper audition.

But how about something cheaper and more accessible than the LPS 1.2, JS-2, or Paul Hynes supplies? The DC voltage regulation gold standard is the LT-3045 voltage regulator. The best implementations cascade these in series to improve voltage regulation (using ultra clean DC power to power a LT-3045 chip to make even cleaner DC power), and have several of these regulators in parallel to improve current output. I’m a novice at this stuff, but ebay is full of DIY or mass market LT-3045 offerings at very reasonable prices. I have not experimented with any of these yet, but reviews have been mixed.

However, I am eyeing the products at http://www.ldovr.com/default.asp In particular, the single regulated and dual regulated supplies ($95 and $145, respectively). I am also tempted to experiment with the raw boards (~$40) as a retrofit to the OPTO•DX to clear up a LPS 1.2 for the rest of my chain.

In theory, any LT-3045-based supply will have much better regulation than my PowerAdd Pilot2’s. The question is where in my chain will good enough high quality voltage regulation be good enough (vs even better voltage regulation with LPS 1.2 or some future Paul Hynes rail). If a basic LT-3045 supply is good enough (for the Kanex or OPTO•DX for example), that will free up a LPS 1.2 or future-precious Paul Hynes rail for some other component where they can have more impact.

Then there is the whole question of DC cables, shielding options, and grounding options (shunting ground back to a high quality ground, in a star configuration). I have no idea where that journey will go, or how worthwhile it will be, but I was surprised enough by the impact of my Ghent Audio DC cables that I’m now definitely paying attention.

If folks have experiences to share with these or other supplies (and cables), please share! DC power is clearly impactful enough that having a spectrum of available sources will go a long way to optimizing my chain without breaking the bank (or waiting decades for Paul Hynes rails). I’m developing a working theory (aka, educated guess) of what is going on, and I’m eager to try some additional configurations (and read about other’s experiences) to test and develop that theory.

TL;DR - DC power makes a huge impact, and there are a lot of options out there. I’m still a novice at this stuff with very limited experience, and eager to hear what others have learned and experienced.


So What About Clean Power on the Analog Side?

(NOTE: AC power is dangerous and can do serious harm to you, your equipment, your home, and your family…please use a licensed electrician for any AC work in your home, and ensure that everything is done consistent with local electrical codes…no hobby is worth putting yourself, your family, or your home at risk)

With all the upside for clean DC on the digital side, the obvious question is how does clean power impact the analog side of the chain? (eg, DAVE, and in my case, the bass units on my Voxativ 9.87’s)

Several months ago, after some gentle prodding from Roy (@romaz), I actually had a couple dedicated 30A circuits installed to my listening room, with really heavy duty electrical wiring (10-2 Romex) and high conductivity outlets. I use one circuit for my digital chain, and the other for my analog chain (DAVE + the class AB amps in my Voxativ bass units). Since these lines go directly back to my main electrical panel, it has a direct connection to home ground, with a breaker between it and all the other crud in my house electrical system.

It cleaned up a HUGE number of RF gremlins for me (wow!). Once I had this added clarity and resolution, it made it that much easier to hear the remaining digital hygiene gremlins in my system. In the experiments I describe above, it only takes a very brief listen to hear most of the changes, and I no longer have that time of day variability to deal with (the differences are very consistent and repeatable and very clear…makes iterating and experimenting MUCH faster and more effective)

Not everyone has a home setup that lends itself to dedicated electrical circuits for your audio setup. However, if you're close enough to your electrical panel, you can side step a LOT of the chasing down digital hygiene annoyances by spending a very modest amount on dedicated lines. Highly highly highly recommended, if practical for you.

Given this win, I took a leap to experiment some more with AC power hygiene. I recently purchased a used Topaz model 91002-31 ultra isolating isolation transformer. This beast of a transformer has 2500VA output capacity (basically 2500W) so more than enough to drive all my “clean” side kit. The theory is to have two huge transformer coils to buffer any spikes or ripples or other crap on the AC line. For background on this new toy see:

https://www.head-fi.org/threads/top...ansformers-for-affordably-clean-power.857448/

Initially, I heard even more of the clean power awesome (definitely worthwhile), but my unit had an annoying 60Hz hum and ran quite hot. Sometimes the hum was very strong, and other times almost silent (based on my reading, the level of buzz/heat is reflective of the crap the transformer is buffering out). Thus began a love/hate relationship with the Topaz, and day dreams of hiding it in my crawl space or behind a wall (alas, both impractical in my home).

Eventually, I tired of it, and decided to rewire the Topaz in a balanced configuration. Rather than hot being 120V and neutral being a nominal 0V (in the US, our 120VAC single phase home wiring typically has neutral and ground connected at the electrical panel), in a balanced configuration, hot is positive phase 60V, and neutral is negative phase 60V (with ground at 0V). In this configuration, the Topaz all of sudden was near silent, and ran MUCH cooler. Except for being a hideous block of metal, I now have nothing but love for the Topaz (CAUTION: Balanced power has particular rules for wiring, and not all devices are safe with balanced power…make sure your electrician knows how to work with balanced power, and make sure you’re not introducing ground faults between neutral and ground, and that all your power switches are double poled so they operate on both neutral and hot!)

Based on the positive experience with my analog chain, I bought a second Topaz, and have it wired in balanced mode for my digital chain, also on a dedicated circuit. Once I have completely optimized my digital chain, I’ll do real A/B tests on the digital side, but for now, big win on the analog side, and TBD (if any) win the digital side.

So all that is well and good, but what is that last wrinkle I mentioned about power hygiene on the analog side of the chain? (remember, by definition, the DAC lives in both the digital chain and the analog chain, and is impacted by both).

As I sat back with a big grin on my face listening to the best my system has every sounded, I reassessed my system based on what I’ve learned. It turns out I have two additional components that are mains connected, but they are in my analog chain (and connected in two different ways to my DAVE, so they definitely need my attention). Each of my Voxativ Pi bass units are connected to the XLR outputs of my DAVE, and have a built in 200W class A/B amp that are plugged into the same balanced isolation transformer as my DAVE, on the same dedicated 30A circuit I use for my analog chain.

As a final sanity check, repeated some listening tests with the Voxativ Pi Bass units unplugged from mains and from my DAVE. In this scenario, DAVE is the only mains connected device (through an isolation transformer to a dedicated electrical circuit), with Hugo mScaler mains isolated by a battery and optically and mains isolated on both input and output. This is now the most isolated I can make DAVE, with my best DC power dedicated to feeding the final component before Hugo mScaler (the Kanex HDMI audio extractor), and my best DC power dedicated to feeding the final component before DAVE (the “clean” side of OPTO•DX).

As a baseline, I listened in my above new optimal configuration, but with the bass units plugged in and connect to DAVE, turned on, but with the volume controls on the bass units turned all the way down. It took a while to acclimate to the new tone and find some passages in test tracks that were particularly challenging. Once I thought I had a good handle on it, I unplugged the bass units from the wall and removed the connections to my DAVE, and listened again.

With the bass units removed from my system, I heard a very small decrease in harshness and sibalance on some particularly challenging passages in some recordings (we’re talking slight here). Huh.

I reran the listening tests, but this time with the bass units plugged in and on, but with the connectors disconnected from the DAVE. Basically, is the vector for the noise back through the the XLR/RCA cables connecting my DAVE to the bass units, or back through the mains AC cables to the DAVE via DAVE’s mains connection?

With the bass units disconnected from the DAVE, but plugged into the wall and on, the slight increase in harshness was back. Clearly I have some work to do to insulate mains leakage from my bass units back to my DAVE. Huh^2.

As a next to last experiment, I moved my bass units to my dedicated digital outlets, leaving my DAVE and balanced isolation transformer as the only things plugged into my dedicated analog outlets. Now that little bit of extra harshness was gone again. DAVE appreciates having a moat on all sides, even the AC side!

As a last experiment, I moved my bass units to my dedicated analog circuit outlet, but connected at the wall, with DAVE connected to my balanced isolation transformer connected to the same outlet. Basically is the balanced isolation transformer capable of blocking any nasties from getting from my bass units to my DAVE?

Alas, only partially yes. I’m still hearing a hint of the harshness I heard before, but much decreased (I have to listen very carefully to catch it). I’m getting the best isolation by having the Voxativ bass units on a completely different circuit, and isolating DAVE on its own circuit behind an isolation transformer.

So how the heck is stuff getting through a big ass balanced isolation transformer from a class AB amp? (not even class D!!!). Even if I’m only hearing it on some extremely difficult passages where recording quality is already on edge, the fact that I can hear it at all is mind blowing, and reenforces how every little thing and every little vector is worth paying attention to.

There is a lot more to be said about my journey (so far) in analog chain optimization, but that is for some future opus. The TL;DR: get rid of EVERYTHING you possibly can, get the most transparent and ideal DAC you can (Chord DAVE), get the cleanest power you can, and get the fastest and most dynamic transducer you can (Voxativ 4D in my case, but I’m dying to hear the new 4phi drivers).

TL;DR - Component minimalism and clean power are ULTRA impactful on the analog part of your system. Anything you can do to isolate and minimize your analog components and get them clean power will be handsomely rewarded. Isolate your DAC mains as much as you possibly can. Much more to talk about on the analog side, but alas this write up is already too damn long.


Dang, This Is Tough to Follow…Can You Draw a Picture?



Note: there are some redundant options shown here (for example I usually power the HMS with the stock supply, but many of the above experiments are with the HMS powered by a PowerAdd Pilot2 battery. Similarly, if using optical in on the HMS, be sure to disconnect the USB path to make sure the HMS is electrically isolated. Lastly, when the “dirty” side of the OPTO•DX is powered by PowerAdd Pilot2, only the “clean” side is being powered by the LPS 1.2.


So What Did I Learn?

When it comes to isolating your digital chain from your analog chain, there is nothing better than an optical air gap

• No matter how much you filter on an electrical connection, there is always a residual something that can impact your DAC
• Put an optical air gap as close to your DAC as you possibly can
• Yes, bits are bits, but you can help your DAC immensely by making sure that only the bits get into it (and not all the crap that can come along with them)

Optical isolation is awesome!

• The AudioWise OPTO•DX is the digital optical moat I’ve been waiting for since I first got my Chord Blu2 to pair with my Chord DAVE…bravo Dan!
• The bang for the buck for putting a moat as close as possible to your DAC can’t be underestimated (cleans up a LOT of upstream sins)
• Even with the moat, I’m still some hearing small differences in upstream tweaks (although MUCH smaller than before)…they’re still worthwhile (for me), but you’re sitting pretty close to pinnacle audio with Chord Hugo mScaler and OPTO•DX

Holy crap, does clean well regulated mains disconnected DC power matter!

• Even a crappy little battery AA battery pack is a great diagnostic aid to see if investing in DC power hygiene will make a difference (hint: it really does)
• Closer you are to your DAC, more important better DC power is
• Great voltage regulation really matters (a LOT), and seems to have a bigger impact than mains isolation (on most kit)
• Have power supplies that are a LOT beefier than you need really matters (surprisingly true)
• Being disconnected from mains really matters (AC leakage, ground loops, etc), but high quality and stable voltage regulation seems to matter a lot more
• I’m surprised how much of a difference well shielded DC cables make (keep them as short as possible)…lot more to learn here

AC power really makes a difference, esp. for your analog chain

• If your listening space is remotely close to your electrical panel, put in some high capacity dedicated power lines, with beefy 10g wiring (WOW!)
• Isolation transformers are pretty cool, and protect the mains side of your analog chain
• Isolating your DAC on its own dedicated circuit is even better still

So What Is My Current Recipe?

With the caveat that noise and noise management is COMPLETELY environment and equipment dependent, here is my current recipe for digital nirvana with Chord Hugo mScaler and a Chord DAC.

• Use the optical input to your Hugo mScaler for the quickest path to highest quality audio. If you have the patience, USB input can be better still, but harder to get it to pinnacle levels. Even with optical, source quality (and power quality on source) matters, and I have no idea why. I am using a Kanex HDMI digital audio extractor connected to a NUC streaming endpoint, powered by an Uptone Audio LPS 1.2 DC supply. For quick and dirty, a Chromecast Audio puck ($30 used) powered by a clean DC supply is an amazing optical Roon endpoint for the Hugo mScaler. My next step is to elevate my USB chain based on these findings, so I can get more out of my higher resolution content.

• For Hugo mScaler, get the best DC supply you can possibly (most stable ground and reference DC voltage, fast with lots of reserves, ideally mains isolated if you can), pair it with a high quality DC cable (as short as practical, preferably shielded), and operate the DC supply at 15V and as far away from its current limits if you can (you don’t want to be straining the supply…you want it to have plenty of reserves to react to anything that is impacting the ground or reference voltages). I am using a PowerAdd Pilot2 battery (at 16V), but I have a Paul Hynes SR4 (and eventually a Paul Hynes SR7 DR rail) on order.

• Use an OPTO•DX to optically isolate the dual BNC output from your Hugo mScaler from your Chord DAC. Ideally, separately power the “dirty” and “clean” sides with high quality DC 12V power (mains isolated makes a difference), with the better supply (if you have to choose) on the “clean” side. The Uptone Audio LPS 1.2 is an excellent choice. DC cable quality makes a huge difference here as well.

• Isolate your Chord DAC (electrically and optically) as much as you possibly can. I have a dedicated electrical circuit, balanced isolation transformer, and no amplifier attached to my Chord DAVE (I direct drive single driver high efficiency Voxativ 9.87 speakers). If you have a Chord DAC that takes DC input power, I suspect you’ll get a win by mains isolating the DAC and having cleaner DC power as well (not verified by me).

• If you make any meaningful change in your DC chain, go back and revisit the other pieces. You may be surprised that the noise profile of your system has changed, and that there are different optimal configurations to be found.

Conclusion

I will be purchasing an OPTO•DX day one when Dan posts them up on his site. It is now a core part of my system, and Dan can’t have my preproduction units back until I receive my production unit. I recommend the OPTO•DX without reservations to all mScaler owners. With it, I am finally able to retire my Ferrited Cable of Shame, and no longer have to explain that monster to people that visit my home (“What the hell is that thing?” “It filters out RF that impacts the ground plane of my DAC” “I’m sorry, what’s a dack?”).

If your budget allows, I strongly recommend that you at least audition a premium DC power supply (ideally mains disconnected) like the Uptone Audio UltraCap LPS 1.2 and see what sort of difference it makes for you. Alex offers a very generous 30 day fully money back policy. Do yourself a favor and take him up on it and see if it works for you (I have no commercial relationship with Uptone Audio…I just love the work Alex and John are doing, and respect the stand up way they run their company). I’m sure there are even better power options out there. When I (finally) get my Paul Hynes supplies, I’m looking forward to repeating these tests to see how this scale with power quality.

I am far from an expert on DC cables, but if the LPS 1.2 makes a huge difference for you, get a high quality shielded DC cable from folks like Ghent Audio (price is right too). Again, I’m sure there are other great options out there. Given the lift I heard with the Ghent cables, that is definitely on the list for future experimentation.

I’m finding what a lot of others have already discovered: you can never have too many ultra high quality DC rails, even the lowliest digital equipment benefits from better DC power, there are always difficult Sophie’s Choices about which component gets the best power, and all this makes the excruciating wait for precious Paul Hynes SR7 DR rails 100x more painful.

If you’re serious about optimizing digital audio, get an OPTO•DX to optically isolate your Chord DAC from HMS, and as many high quality DC cables and power supplies as you can afford, and start experimenting to see what makes the biggest difference for you.

My next step is to take my above learnings and reassess how I lay out, power, and connect my equipment (are there less expensive power supplies that are good enough? Can I lose the batteries but keep the SQ? Will even better power supplies elevate things more? etc). With that done and system stabilized, the itch will return, and it will be time to see if there is even more magic to be found by diving ever deeper into the rabbit hole.


Whew…

As I reread the above, I find myself shaking my head in awe at the amazing audio journey I’ve been on the past several years. As is clear from my Blu2 review, I used to think that mScaled music was the ultimate, and there was no way things could get better. Boy was I wrong. In ways known and unknown, the rest of my system was holding it back.

Since mScaler finally gave me an absolute reference, seemingly every month or so, I’m once again hearing the best sound quality I’ve ever heard. Amazingly (and wonderfully), I’m finding that ultra fast transducers, absolute minimalism in your analog chain (no speaker cross overs, no amps, etc), obsession over power quality and stability, and relentless digital hygiene continue to reveal more and more (and MORE) magic and emotion in the music. The mScaler sets an absolute reference. As such, it handsomely rewards supporting equipment that takes away as little as possible from that reference.

Getting past all the equipment and speaking to the music, the humbling thing for me is the realization that all this amazing emotion and magic was in the recorded music all along, but that hadn’t been heard and experienced except by those precious few that were in the studio for the original recordings. What an unexpected blessing and gift to be able to experience music like this!

All that being said, the more I learn and hear, the more optimistic and excited that there is even more to learn and hear. Incredible stuff, and a true gift to be able to experience this level of artistry in our living rooms.


Addendum

9/14/19

To the question of whether I have tried my new Paul Hynes SR4 in this setup, I have. SR4-19 (@15V) has a huge positive impact powering the HMS (vs PP2 battery). It also has a huge positive SQ impact when powering the end point NUC @ 19V, with the HMS on PP2 battery. I slightly prefer the NUC End Point on PP2 @ 19V + SR4 @ 15V on HMS combo, to the NUC on SR4 @ 19V and HMS on PP2 @ 16V combo. Alas, I don't have 2 SR4's to see what the marginal lift is by running both the end point and HMS on SR4's.

My current setup is end point NUC on PP2 battery at 19V, USB out (via Lush^2 USB cable) to ISO Regen (on LPS 1.2) to USB out (via USPCB) to a Matrix Audio XSPDIF 2 DDC (powered via USB from the ISO Regen, so LPS 1.2 sourced power) to optical toslink to HMS. I am also powering the TX side of ODX with a PP2 battery, and the RX side of ODX with a LPS 1.2.


9/15/19

My NUC on Paul Hynes SR4 had a huge impact, almost as much as when I had the SR4 on my HMS. I was surprised.

My core theory is that anything touching reference voltage or ground plane on a DAC is audible. Anything that does not can not (assuming bit perfect). Anything we hear can come from the outside, or be induced in the DAC. Somehow, power to the NUC was impacting what was getting to my DAC (through USB regenerators and DDC to optical toslink)

Here is my working theory:

Perfect power supply does the following:

• Insulates device from electrical cruft from outside world (these will impact ground and reference voltage in the device, which may work down the the chain)
• Prevents electrical cruft from device getting to outside world (do no harm)
• Prevents ground loops (corrupts ground plane, which will impact everything connected to that ground plane)
• Has perfect voltage regulation (low ripple, stability) (reference voltage needs to be stable and reference)
• Has huge current capacity and fast response to changing loads (don't want instantaneous current draw to impact ground or reference voltage)

Battery will get you some of these (mains isolation, etc), but they actually have poor voltage regulation and slow transient response. When powering my NUC with a PowerAdd Pilot2, I hear an improvement, but no where near as big as an improvement I hear with the SR4.

Based on this, the internal loads on the device can self-induce noise on the ground and reference voltage planes, and somehow those are getting propagated to the DAC, either through direct connection or getting induced in the DAC. It can be over the air (RFI) or something to do with signal integrity in the optical signal that is inducing noise in the DAC. Could the receiver chip in the DAC be inducing noise in the DAC based on the signal integrity? Don't know, but two ISORegen USB regenerators in series sound clearly better than 1 in my

By having the best PS you can get for anything close to the DAC (including the DAC), when there is a big current demand, it protects the device from having the lights dim, which whacks reference voltage and ground plane.

Anything touching reference voltage or ground plane on a DAC is audible (ditto clock, but I haven't done anything with clocks yet) You will not hear anything does not (assuming transmission is bit perfect). The maddening thing is trying to come up with theories for how things way away from the DAC could be influencing the DAC.

Previously, I did an extensive review of the Chord DAVE vs Hugo2 vs Mojo DACs, when driving various headphones, my traditional 2 channel system, and (in what was a turn-my-audiophile-world-upside-down revelation) direct driving high-efficiency single-driver Omega Super Alnico Monitor speakers. I was hoping to include the Chord Blu2 in the review mix, but unfortunately my Blu2 did not arrive until a month or two after I had to return the loaner Hugo2 unit. My original plan was to update that review once I got my Blu2 in, but my experiences over the past couple weeks are such that the Blu2 really deserves its own chapter.

This review may be most helpful if you first scan the original DAVE vs Hugo2 vs Mojo review, where I detail my equipment/biases/expectations/hopes for music, as well as provides a baseline for the core DACs in the Chord DAC family that the Blu2 is intended to enhance and extend. That review can be found here: https://www.head-fi.org/showcase/chord-hugo-2.22209/reviews#review-19435


Hardware

Source setup
MacBook Pro and Mac Mini, running latest OS X, content on local SSD, running Roon 1.3
Bit perfect either direct USB, or via direct ethernet to a Sonore Sonicoriber SE running Roon Bridge to USB, to the DAC
Chord Blu2 CD transport ($10000)

DAC setup:
Chord Hugo2 ($2400)
Chord DAVE ($10000)
Chord Blu2 mScaler ($10000)

Headphone setup
Sennheiser HD800 (with SR mod) ($800 used)
Audio Zenith PMx2’s headphones (heavily modified Oppo PM-2’s) ($1800)
Noble Katana CIEMs ($1600)
MrSpeakers Aeon Flows headphones (closed) ($800)
Grado HP1000 (HP2) legendary old skool headphones ($priceless)

Traditional Two Channel Setup
RCA from DAC to Benchmark AHB2 amp ($3000) to B&W 802D3’s ($22000/pair)

Direct Two Channel Setup
RCA direct to Omega Super Alnico Monitors ($2000/pair)
RCA direct to Omega Compact Alnico Monitors ($1500/pair)
For Chord DAVE and Omegas, XLR direct (in parallel) to JL Audio F112v2 subwoofer ($3700), tuned to room and low end fall off of Omegas (~50Hz)
For Chord Hugo2 and Omegas, no connection to subwoofer
For B&W’s, no connection to subwoofer

DAC settings
For headphones, cross feed set to 2 for DAVE and Hugo2 (no crossfeed setting on Mojo), unless recording is binaural (0 crossfeed)
Neutral filter for Hugo2
PCM+ mode, HF filter off for DAVE (per recommendation when using Blu2)
Dither off, and by default high resolution mode on the Blu2
All DACs volume matched using a SPL meter (at least to the best I could)


Content

At various points, I went through all the music in my “Go-To Chord DAC Demo tracks” that I highlighted in my Chord DAVE vs Hugo2 vs Mojo review, but for these sessions I really focused on the following, either for how much they shined in my previous review (could they shine brighter still?), or how much they fell short (could the Blu save them?):

Murakkaz Ah Ya Muddasin, from “The Splendour of Al Andalus” by Calamus (MA Recordings, DSD64)
Remarkable recording in what sounds to be a majestic and spiritual centuries old cathedral in Spain. With the right equipment, you are transported to a place you’ve never been to but always want to get back to. When the full group joins in, it is profoundly challenging to reproduce the mids and highs without sounding shrill and congested. When the reproduction is effortless, it is magical (to say the least…my jaw drops every time when it’s “right”) If the sound chain is able to maintain that glorious soundstage, it is off the charts. Todd Garfinkle is a magician behind the microphone.

Noche Maravillosa, from “Salterio” by Begonia Olavide (MA Recordings, 16/44.1 FLAC)
Another gem of a recording and performance from Todd. The precision and clarity of the instruments (particularly the percussive ones) is intoxicating and tangible.

Rimsky-Korsakoff: Scheherazade, 1st movement conducted by Fritz Reiner (Analogue Productions Remaster, CD layer from SACD)
The most perfect recording of the most perfect performance I’ve ever heard. Listening to this recording on a transparent system is a life changing experience: you are standing with Maestro Reiner in Chicago as his orchestra reaches for a performance for the ages. A cultural treasure, and worthy of building a world class system around.

Handel: Messiah - Chorus. O thou tallest good tidings by Dunedin Consort (Linn, CD layer from SACD)
Handel: Messiah - Hallelujah by Dunedin Consort (Linn, CD layer from SACD)
A magnificent recording, reconstructing the original version of Handel’s Messiah, with a total of 12 singers. The normal complexity of the piece is captured in a way where you can hear each voice in the chorus, and how it comes together into a larger whole. An amazingly intimate performance when the reproduction chain can manage the complexity and dynamics and not have the soundstage become muddy and flat.

Arnesen: Magnificat - Fecit potentiam by TrondheimSolistene (2l, 24/192 FLAC)
This is such a lovely recording at any quality level, but goes from incredible to other worldly as the chain scales up. The orchestra, choir, and church should all have equal contribution to something far greater than the sum of its parts. When it all comes together, you can feel the three core elements feeding off each, creating a profound joy that is sweeps you into euphoria.

Stardust, from “Duets” by Rob Wasserman (16/44.1 FLAC)
Every track on this album is a gem, but this one is particular is a fantastic test of sound stage and imaging. At its best, you hear each backing voice precisely in space, but still presenting as a harmonious whole. In real life, detail and precision spatial placement isn’t hard and clinical, why should it be in reproduction?

Shamas-Ud-Doha Bader-Ud-Doja, from “Shahen-Shah” by Nusrat Fateh Ali Khan (16/44.1 FLAC)
The first track from what was my surprise 2012 album of the year (see http://thingssoimpossible.blogspot.com/2012/12/2012-albums-of-year.html for that backstory, with the surprise ending). A remarkable supremely spiritual performance by a remarkable man, captured in an “eh” recording. The question for me is what these DACs can do to elevate a middle of the road recording that is worthy of elevation.

One World, from “Session 1” by Sareena Overwater (Blue Coast, DSD64)
One World (Instrumental), from “Session 2” by Sareena Overwater (Blue Coast, DSD64)
Real magic from Cookie. These tracks are wired directly to deeply held memories for me, and the stronger the reproduction chain, the stronger the emotion that they evoke. There are better examples of piano performance and better examples of vocals, but the emotional truth and power of this performance is unmatched. More on this track at the end of this review.

Vous et Moi, from “Night and Day” by Willie Nelson (SurroundedBy Entertainment, 24/96 FLAC)
What if Willie Nelson was in a dispute with his label, got pissed off, and invited the best musicians he knew to the studio to record an instrumental album in full surround? Yeah, this actually happened, and it is as awesome as you think it is. The album is amazing in a musical surround setup, but a proper 2 channel system puts you right in the middle of the band. Incredible stuff.

All I Want, from “After Blue” by Tierney Sutton (BFM Jazz, 16/44.1 FLAC)
Tierney Sutton has a striking clear and present vocal style, and that is on full display on her “After Blue” album of Joni Mitchell standards. I continue to be amazed how ever better DACs extract ever more nuance and subtly of performance from top tier vocalists. It is a joy to hear the depth of craft and art of vocal performance on tracks like this.

Rosa fresca, from “Il viaggio d’amore” by Arianna Savall and Petter Udland Johansen (Carpe Diem, 16/44.1 FLAC)
“The journey of love” is a marvelous exploration of love through the ages, from multiple cultures and times. The whole album is a joyous wonder, but the opening track (“Fresh Rose”) of a traditional song from the 1500s is an invitation to join in joy and unbounded hope. The company of players is feeling it, and you do too. When you’re hearing every string pluck in the strums and the voices comes together into something much larger than the sum of its parts, you’ll be glad you accepted that invitation.

L’Amor, from “Bella Terra” by Arianno Savall (Alia Vox, 16/44.1 FLAC)
If “Rosa fresca” makes you fall in love with Arianna Savall singing about love, you’ll want to seek out her “Bella Terra” album. An accomplished harpist and vocalist, Savall is at her best when she brings both together: voice and instrument are one, and evoke marvelous sound and emotional resonances in each other.

Stuck In A Moment You Can’t Get Out Of, from “Open Your Ears” by The Persuasians (Chesky, Binaural 24/96 FLAC)
One last gem from Chesky. There is a profound difference to listening to a recording of a group of people sing, and being with a group of people that are singing. This is another recording that (at least for me), when you cross some magical threshold of transparency, the people become real.


Background and Expectations

I can’t recall being more excited and impatient as I have been for the Chord Blu2. The presentation materials from 2017 CES launch were a tour de force, and it was clear that the Blu2 could potentially represent a long sought after but almost never achieved audio end state. When I purchased (and was blown away by) my DAVE mid 2017, I could literally only imagine where the Blu could take something that was already well beyond what I thought was possible in music reproduction. I preordered and paid for mine in May (my first dedicated CD player purchase since I got my Nakamichi OMS-5A in 1984!), and proceeded to wait through countless delays until I received my Blu2 six months later. As impossibly high as my expectations were, the Blu2 has blown them away in every way.

First some background for those that are not familiar with the Blu2. It is a CD transport with a built in digital interpolation and upscaling filter (what the designer Rob Watts calls mScaler) that operates at an effective one million taps (vs ~25k taps for Mojo, ~50k taps for Hugo2, and ~150k taps for DAVE). According to Rob, in the 80’s he calculated that you needed ~1M taps to be able to reconstruct the original analog signal from a 44kHz digital signal to the limits of what is perceptible. At the time, that was an impossible objective (taps were measured in 10’s, not millions). As time and technology has progressed, the Blu2 now has the compute capacity to execute a 1M tap interpolation filter in real time.

To give you a sense of how insane insane a 1M tap filter is, with the Blu2, the value for the audio at any given instant in time is calculated from all the data in a 1.4 second window around that instant in time (backward and forward). That level of compute is beyond crazy, but it is why Rob uses advanced FPGAs in his DACs that include hundreds of digital signal processors running at the same time.

So how the heck can a sound 1/2 a second in the future or from the past be impacting what I hear right now? That’s impossible, right? The idea is that when the original analog sound was digitized, the digitization process actually took that analog signal and smeared it out over that time window (forward and back in digital time). The original signal is still there, but you have to apply incredible compute to extract it and use it to interpolate the original analog signal. That is what the mScaler is doing: reconstructing the original analog signal based on the math of how analog signals are transformed when digitized. The more taps you have in your interpolation filter, the closer you get to the original analog signal.

The main impact of this is in the precise timing of when sounds start and stop. The unbelievable performance of the WTA filter in the Chord DACs is what (in large part) contributes to the phenomenal sound stage and resolution and sense of physicality you get from these DACs. The mScaler (in theory) represents an end game where the filter reconstructs the original analog signal to the limit of what is humanly perceptible for any given piece of digital content, in this case, all from a lowly traditional CD.

So why the heck would one buy a $10k CD player in 2017, and why pick a CD player of all things to be the first product with a breakthrough technology like the mScaler? The Blu2 just happens to be the product that was first in the queue when Rob finished his next generation WTA filter on the next generation FPGAs. After doing the work to get to a 500k tap WTA filter, the improvement he heard was so significant that he doubled down and did the hard work of pushing it to 1M taps. Since the transformation was so significant, he then spent 3-4 months adding USB support to the Blu so more people could take advantage of the mScaler.

The Blu2 has a cd transport (Phillips CD Pro 2 mechanism), but it can also accept USB digital input (up to 768kHz) and digital BNC coax (up to 384kHz) as input, and put that digital signal through the same mScaler filter. Whatever the digital source, once the mScaler has upsampled the digital signal (up to 705kHz or 768kHz, or 16x) it outputs the upscaled digital signal to your external DAC. The Blu2 has dual BNC coax outputs (up to 768kHz, preferred for DAVE and Hugo2), as well as a traditional coax digital output (up to 384kHz) and dual data AES output (up to 192kHz).

Special to the advanced Chord DACs is the ability to use dual digital coax, to support 704-768kHz (16x) signals. The Chord DAVE was designed 3 years ago anticipating the advent of the mScaler (yes Rob is playing a very long game). It has dual coax inputs that accept up to 768kHz signals. The recently released Chord Hugo2 has a 3.5mm dual coax connector that can accept the sample inputs. When you have dual coax connected from the Blu2 to the Chord DAVE or Chord Hugo2, both DACs autodetect that there is a dual coax connection and switch into a special mode where they use both coax inputs simultaneously.

When you connect to the coax inputs on the DAVE or Hugo2, you bypass the 1st stage of the WTA filter in the DAVE and in the Hugo2. These is the stage that does the heavy lifting of applying the taps to interpolate and reconstruct the original signal. The DAVE and Hugo2 then have the 2nd stage (volume control, cross fade, etc) and the digital to analog output stage. Connecting the Blu2 to these DACs effectively turns your DAVE into a 1M tap DAC (vs ~150k taps) and your Hugo2 into a 1M tap DAC (vs ~50k taps)

Net net: when you run a Blu with DAVE and Hugo2, you have the identical 1M taps. The main difference between the BluDAVE and BluHugo2 in the higher quality and more powerful output stage of the DAVE, better isolation on inputs (I believe) on the DAVE, better power supplies on the DAVE, more filter options on the Hugo2, 2 dual digital out options on the DAVE, etc.

For giggles, the DAVE has two different dual digital outputs. You can actually connect these to a Hugo2(!). When you have a Blu connected to a DAVE, the Blu signal is passed through to the dual digital outs on the DAVE. That means in theory you can run a BluDAVE and two BluHugo2’s simultaneously (woah...how cool is that?). Alas, not as cool as it may seem. According to Rob, the DX outputs of the DAVE are not galvanically isolated. That means that BluHugo2 will sound better than BluDaveHugo2, by how much highly dependent on your setup (in my setup, this was quite a bit)

For those not following at home, Rob has announced that he is working on a digital amp that takes the final digital to analog stage of his DACs and ups the output power to be able to drive traditional speakers. The first is targeted to be 20W, with higher power units in the future. Presumably a future digital amp would take dual coax inputs, and handle the final digital to analog output stage with a higher output power (20W vs 1W with Hugo2 and 2W with DAVE). He has also announced that he is working on an analog to digital convertor (called Davina) that uses the same mScaler technology to optimize the digitization stage and eliminate the artifacts/signal loss/aliasing that is common to traditional ADCs. The combination of theoretically perfect analog to digital conversion (Davina) and theoretically perfect digital to analog conversion (BluDAVE) will be an opportunity to close the loop and validate the theory, and address any gaps between reality and theory. Incredibly exciting stuff.

Presumably, next would be a digital crossover, effectively connecting a digital amp to each driver in a speaker to eliminate transparency loss from the speaker cross over network, but nothing announced on that yet. A digital cross over would (in theory) be a perfect opportunity to do any transducer correction or room correction, esp. if you have a Davina and BluDAVE in the mix (again, all conjecture on my part...nothing has been announced in these areas, but Rob clearly has life long mission that he has been systematically and effectively executing against).

For now, when using a Blu2, I think of the DAVE as a 2W digital amp and the Hugo2 as a 1W digital amp.

So based on available information and my experience with Mojo vs Hugo2 vs DAVE, going in I would expect BluDave > BluHugo2 (although not by much), and that both would be >> Dave (by a lot), with the Dave already >> Hugo2 (by a lot).

Spoiler alert: I was right

Also my expectation bias going in for the Blu2 CD is that it is a novelty that I wish I didn’t have to pay for and not something I would use (I already have all my music ripped, and streaming from a Roon core to a Sonore Sonicoriber SE running Roon Bridge to USB, to my DAC).

Spoiler alert: I was not only wrong, but this represents the second time in the last couple months my audiophile world has been completely and utterly turned upside down.


First Impressions

After 6 months of waiting. my Blu2 arrived while I was overseas on a business trip (arg!). Coming home. I don’t know if it was the 28 hours of travel or the Blu2, but after quickly wiring in the Blu2, Nusrat Fateh Ali Kahn lived again, and he was performing live in my living room. I never thought in my life that I’d hear the man like this. Wow. Truly a blessing to be able to experience this.

At a pragmatic level, the magic that DAVE brings to vocals and stringed instruments, BluDAVE brings to woodwinds and horns. Having not had a lot of first hand experience with these instruments, I had no idea how much depth and subtly was hiding there.

More broadly as a holistic experience, BluDAVE is by far the most artful music reproduction I have ever heard, and even exceeds many of my live music experiences. To explain, I believe that every performance has artistic merit (art being defined as the capture and conveyance of some sort of emotional truth or idea). The performer is working to convey something, the audience is working to receive it, and the engineer is working to capture it. If a reproduction chain is able to reproduce that, even if poorly captured, it is akin to a time machine and transporter rolled into one. It is very rare that I don't enjoy listening to some new piece of music and finding that artistic intent. It may not be for me (so I may not go back to it if I don't care for it), but I appreciate and celebrate what is there, and that it has meaning for other people. I learn as much about myself from things I find resonances with as from things where I don't (and often more from what I don't care for). I also learn more about what matters to other people who resonate more with that sort of thing.

In the case of Nusrat Fateh Ali Khan, listening to that performance with the Blu2 was the first time I was able to completely feel like I was in the room with those musicians and that audience (vs getting afterimages and hints) and got completely swept away. Incredible experience. Shifting to some Coltrane, it was scary real to hear the man be so alive and present.

Shifting to BluHugo2, preliminary feedback is "blissful", "infinite air", "never heard that before", "really evolves the listening experience", "wow you can really separates the headphone wheat from the chaff now”. Incredible stuff.

However, right off the bat we found surprising sensitivity to details/mechanics of the BNC connection between the Blu2 and the DAVE/Hugo, which made more systematic comparisons more difficult. After iterating through N permutations of 3 sets of cables, ferrites, Blu2, DAVE, Hugo2, headphones, Omegas direct, and Benchmark/B&W combos, some patterns started to emerge (wow, I've never heard the B&Ws sound so good!) but also some head scratchers. There is work to do here to get to a stable optimal configuration, and I’ll share our experiences in that journey a bit later on. But first, let’s start with the music.


BluDave vs DAVE

So double clicking down, what does the Blu2 do for the DAVE? BluDAVE gives one an almost superhuman ability to focus on individual performers and the subtlety and nuance of each performance (snare across the drum, subtle bending of strings, the dynamics of a strum, the pluck of a finger pick, etc.) while being able to hear the performance as a whole at the same time. It is a surreal experience for reproduced music, and the best I can describe it is like the feeling when you’re at a concert, and you focus your attention on the bass player (or whomever) and really get a sense of what they’re bringing to their individual performance, while at the same time hearing all the musicians act and react to each other on stage.

In particular, percussion (which was already spectacular with the DAVE), becomes a vivid and present dance with the BluDAVE. For vocals (another DAVE strength), the BluDAVE captures (remarkably) even more nuance and expression…when you close your eyes, it is not a challenge to imagine how the singer’s facial expression and body posture and movements must have looked like during the recording session. The sense of intimacy and presence that the DAVE has (which I already thought was beyond what was achievable in music reproduction) is taken to a completely next level. Wow.

Where previously I characterize the soundstage with DAVE and Hugo2 and Mojo by number of “zones”, with the BluDAVE the soundstage is now effectively continuous (infinite zones). On the best recordings, it is almost holographic (including depth, and to a lesser extent, height) The new continuous soundstage makes it remarkably natural to place a singer or instrument in space, and even (for some recordings) to get a vivid sense of the surrounding room they were recorded in(!) For choral pieces or ensemble pieces, the effect is particularly vivid and immersive: hearing the different rows of a choir and the different heights of the singers is unexpected WOW moment, as is the clarity and vividness of each voice. When the vivid details blend into a seamless whole, the sense of the physical presence of the performers and being part of the performance is glorious. I’ve gone from listening to choral music <2% of the time, to >50% of the time. Completely magical and revelatory.

As pieces get more complex, the more effortless the chain becomes. Listening to some of these more complex pieces (orchestral, etc) with BluDAVE is a revelation: there is no blurring or collapsing of the stage and performers. All that magic from the more intimate pieces where DAVE is world class persists with even the most complex pieces I throw at it. Being able to immerse myself into the layers and complexity and still be swept away by the nuance of the individual performers in an orchestra is a stunning experience. There is so much more to these performances to cherish and enjoy. For a modest orchestra, you can distinguish the individual players and how they’re arrayed around the conductor. For very large orchestras, there are hints of the individual players in the best recordings, which gives me hope that with better recordings and reproduction, there is so much more detail and reality to be revealed.

As I listened more to BluDAVE, it became clear that it has the power to shine the light of a 100 suns on everything in the reproduction chain: content, mixing, speakers, headphones, etc). Pieces that I thought had no upper bound (better the equipment the more they revealed) all of a sudden hit a wall and you could hear the limits of the recording very clearly. While my B&W/Benchmark chain was recreating sounds at a level I had never heard before, it was clear that they were the limiting pieces in the chain. Even my Sennheiser HD-800’s were clearly topped out, and I had to do all my critical evaluation of the BluDAVE and BluHugo2 driving my Omega Super Alnico Monitors direct. Very humbling experience to so unambiguously hear the limitations in the rest of your chain and content, but also exciting because it is so clear when you’ve changed something for the better. These are not subtle audio queues that different people hear and interpret differently; the truth is laid bare by the bright light of BluDAVE.


BluDAVE vs BluHugo2

As a reminder, when connected to the Blu2 I think of the Hugo2 as a 1W digital amp, and the Dave as a 2W digital amp. In addition to the output power difference, the DAVE has a 20 element pulse array digital to analog stage, vs a 10 element array for the Hugo2. DAVE also has some advantages in input/output management, etc. All of the interpolation magic is being handled by the mScaler in the Blu2. So the $8000 question: how does a 1M tap BluDAVE compare to a 1M tap BluHugo2, and will I be swapping out my DAVE for a Hugo2?

This is actually a very difficult question to answer with the equipment I have at hand. In practice, I'm finding the Blu2 to starkly reveal scaling limits in content and equipment and transducers that I never knew were there. Fascinating, and remarkably non-subtle...I haven't experienced this level of starkness and obviousness in audio performance ceilings before. If anything in your chain has a limit, the Blu2 will shine a searing spotlight on it.

From my DAVE vs Hugo2 tests, I know my Sennheiser HD800’s are clearly (and significantly) differentiated between the two, but add Blu2 to the mix and my Sennheisers are the clear performance bottleneck in the chain. That forced me to use direct connection to my Omega SAMs for my evaluation, and has started me on a separate quest to find headphones that can scale better with BluDAVE (still in process).

Using the Omega SAMs connected direct (at a reduced volume so as to not push Hugo2 past its limits), qualitatively, I would say if Mojo is an overall 4 and Hugo2 is an overall 6 and DAVE is an overall 10 (using the scale from my Mojo vs Hugo2 vs DAVE review), then BluDAVE is 40, and BluHugo2 is maybe ~25.

Although not a fair comparison, I also compared the BluHugo2 vs the BluDAVE with the Blu set to 1M/500k/250k taps via the filter switch on the back of the Blu2. To my ear, the BluHugo2 is qualitatively just below the performance of the BluDAVE at the 500k tap setting on the Blu2 (medium). As an other qualitative impression, I’d put the Hugo2 roughly 1/3rd of the way between a Mojo and a DAVE, and a BluHugo2 roughly 1/3rd to 1/2 of the way between a DAVE and BluDAVE.

That makes the BluHugo2 pretty damn good! Any Hugo2 owner should be looking for an opportunity to hook up to a Blu2 and hear what is possible, but be open to the fact that your content and digital chain and your headphones will likely be masking what the BluHugo2 is really capable of.

The more I think about it and the more I play with it, the dual coax input on the Hugo2 is a surprisingly clever and remarkably generous addition to the Hugo2. As mScaler gets more prevalent and accessible, the availability of the dual coax input on the Hugo2 is a wonderful way to future proof your Hugo2, while taking as little space as possible so the product can stay portable.

In addition, it makes the Hugo2 much more interesting as a digital preamp for more traditional digital audio. Each of the digital inputs on the coax can be fed independent digital signals from upstream in your chain (up to 384kHz signal each). So if you already have an advanced CD transport or some other digital source, you can wire up to 2 coax digital sources into the Hugo2 and connect a traditional optical digital source to the Hugo2. You can then switch between the 2 coax digital sources, the optical source, and the USB digital source either on the Hugo2 itself or (more importantly) the Hugo2 remote (as an aside, the Hugo2 remote is an absolute game changer...Hugo2 is a world class desktop product, that you just happen to be able to disconnect and turn into a portable).

All this makes the Hugo2 one hell of a desktop digital preamp (with the exception of the DAVE, probably the finest one available). If you have a (literal) end game digital source like the Blu2 (or future mScaler products), you can wire that in, with USB and optical inputs for legacy connectivity. If you have traditional high end digital sources, you can wire up to two of them via the dual coax, and still have optical and USB available.

The only notable gap I see with the Hugo2 as a digital preamp is that it doesn't have a dual coax digital out. That constrains the Hugo2 to be used with analog out only. One hopes that when the digital amps do become available, the Blu2 will be able to connect to them directly, but we’ll all have to (impatiently) wait and see.


So How Did a CD Player Turn My World Upside Down in 2017?

Initially, the CD transport on the Blu2 was at best a curiosity and conversation starter with my audiophile buddies (“Hey, I paid $10k for a new CD player!”). Honestly, I was expecting to play a couple CDs to see what’s what, write a couple pithy sentences about how “Yeah, sounds like the ripped digital tracks, bits are bits, yada yada” then get back to the usual digital tweaking and swapping equipment in and out of the chain to figure out the new toys.

When I finally gave the CD of the Blu2 a listen (direct to Omega Super Alnico Monitors). I was absolutely stunned by the miraculous sounds I heard, even compared to what was already the best I had ever heard (or hope to ever hear) through the USB interface to the Blu. If obsessing over the digital chain can even approximate what I experienced via the CD mechanism on the Blu, I now understand why so many of us invest so much energy, funds, and passion in obsessively optimizing their digital servers and chain. My apologies for every quizzical look and eye roll I may have had in the past; I now understand.

Arnesen's "Magnificat" from 2L is one of my favorite recordings ever, and I have listened to my favorite track many hundreds of times. Via the USB interface to the Blu, it was by far the best I had ever heard (absolutely stunning, and an amazing improvement over even the DAVE). Completely unexpectedly, listening via regular old CD of that track was one of the most emotional and true musical experiences of my entire life (when multiple normally reserved people are simultaneously exclaiming "Oh My screwing God!” during a quiet listening session, you've crossed into a new place). It was one of the most beautiful things I had ever heard, live or recorded, and I literally had tears running down both cheeks by the end of it. Transformational experience.

With Chesky binaural recordings direct from CD, sound stage is at least 270 degrees from listening position, extending well behind me. With binaural recordings and BluDAVE driving the Omegas, I’m experiencing by far the best surround sound I’ve ever heard (which makes sense if the speakers are precisely recreating the recorded sound stage…headphone like binaural experience from speakers…wow!) Listening to Paquito d’Rivera direct from binaural CD redefines a big band experience for me. Absolutely pick your jaw up off the floor magical.

I should clarify that even though the experience was magical and transcendent, I don't believe there is anything magical about CDs or the CD interface (I'm a big believer that bits are bits). The magic is in the Blu itself. With the CD interface, I can fully hear what a remarkable impact the Blu2 can have. Clearly, there are things in my digital chain that are masking or hampering what the Blu2 can do. For me, the Blu2 CD interface sets the benchmark for what my digital chain should be able to do, and how big the gap is that I need to close with the rest of my digital chain (and when I first listened to the CD player, that gap was HUGE) When my digital chain sounds as good as CD direct on the Blu2, it will finally be good enough.

It took me a couple days to recover from this first experience with CD direct to BluDAVE, but my audiophile world got turned upside down; so many assumptions and intuitions no longer applied. Humbled but excited, and more thoughtful and thorough about investigating various practical permutations of kit, but for now, what a joyful time to be alive, to be able to experience things like this.


Cables/Ferrites and Chasing RF Ghosts

So time to chase this down: how the heck can a lowly CD be so glorious, when my modest digital chain fell short?

I have mentioned already the a surprising sensitivity of system performance to digital connections (USB and BNC) in my system. This was not subtle stuff, but more at a “what the hell is going?” level. Even when we were diving into the miracle that was BluDAVE from CD, we had one or two What moments that were due to the USB cable still being plugged into the Blu. Even playing from CD, disconnecting my USB cable from Blu resulted in a very significant improvement in soundstage, a much sweeter and more relaxed presence, the sound stage expanding back to essentially holographic, and (in the case of Magnificat) choral vocals move from a group shimmer to a girls choir with actual individual girls singing their hearts out. High soaring sopranos become something you fly with, rather than waiting for that break.

Overall, the impact from CD with USB disconnected is just glorious. Emotional engagement jumps at least 5x on Magnificat. To my mind, it is as if some sort of phase transition has happened, and my brain is perceiving the sound on the other side of some threshold to reality. What the heck is happening? How can I get to the other side of that phase transition all the time? (it is addictive as hell)

But wait, aren’t bits bits? Is all I’ve learned about electrical engineering and digital compute over the past 40 years out the window? What the heck is going on?

Once past the euphoria and “I can’t screwing believe this” reaction to the CD sound, time for rationality to return. In digital transmission, if you lose bits, it will result in horrible digital noises/clicks/pops, not comparatively subtle changes in sonic presentation and detail. My challenges in my digital chain were not about losing or dropping bits, but parasitic RF noise from the digital chain degrading the performance of the sensitive digital to analog stages in the DAC. While digital processing may be essentially immune to RF noise from the digital chain (parasitic RF noise is different than noise or signal loss in the digital signal!), the digital to analog and analog sections are not.

Back in my graduate school days, my PhD research involved measuring ultra low level signals representing a very small handful of electrons in nanoscale devices. I learned the hard way (and over many many months of chasing RF ghosts), that if you have a Faraday cage, don’t run a wire into it. Is that what was happening for me now?

The magic of the Chord effect is remarkable but fragile; I’m finding it takes precious little to kill that holographic illusion. Chord DACs have tremendous engineering invested in noise management, power management, and isolation. When using the built in CD with the Blu2, you are basically eliminating the external noise vectors through the digital chain. When you connect the Blu2 to the outside world via USB, those vectors return.

So details matter, and everyone’s experience in their setup will be different and unique. Here is my experience and my learnings, which may or may not map to your setup or experience, but hopefully there is value in the sharing.

Let’s start with the USB cables, and sort out why it was having such a profound impact on what we were hearing. Here are the details on what we iterated through:

• Pangea Audio 1.5m USB cable (PCOCC & 4% silver, $35) - This was the cable I was using when I heard the profound difference between CD and USB
• Stock USB cable bundled with Blu2 ($free)
• Tripp Lite 2m USB cable with 2 built in Ferrite Chokes (U023-006) ($6.53)

In addition, based on posts on Head-Fi (thanks @Jawed), I also purchased 40 Topnisus ferrites to play with (https://smile.amazon.com/gp/product/B01E6PLXXC)

During these initial USB tests, I was using the stock Blu2 BNC cables to connect the Blu2 to the DAVE (no ferrites, etc)

So connecting the various USB cables to BluDAVE, here are the results from my listening tests:

Stock Blu2 USB cable >>>> Pangea USB cable (by HUGE amount)
Tripp Lite > Stock Blu2 USB cable (a modest amount, perhaps because of the built in ferrites on the Tripp Lite)
CD direct > Tripp Lite (a modest amount, mainly in refinement)

So time to start adding ferrites to the cable. I focused on trying to improve the Tripp Lite cable, since that was closest to CD direct. After adding 10 ferrites to the Tripp Lite (on the Blu2 end), there was still a gap with CD direct, but it was clearly better than where I started. When I got up to 20 ferrites, quality was very close to CD direct. After getting to 30, very close to what I heard with 20 ferrites, but with perhaps a VERY small improvement from 20 ferrites. In pushing things to 40 ferrites, I couldn’t detect a change from 30.

At this point I found CD direct to be slightly better than the ferrite-loaded Tripp Lite cable (more space, and slightly better imaging), but very close. I hit diminishing returns on ferrites somewhere between 20-30 ferrites, with no downside (other than a deep personal shame for having a USB cable with 40 ferrites to have more ferrites on the cable.

So USB cable really matters (at least having the wrong one in the Pangea) and ferrites make a clear audible difference. What about the dual BNC cables?

Remember that I was hearing a lot of variability and lack of consistency in my initial assessment of cables when my BluDAVE was in my cabinet. I suspect the cables were brushing against power and USB cables, etc. To avoid physical layout issues, I had my BluDave on my coffee table so I could make sure cables aren’t touching anything, and the inconsistency went away.

Here are the BNC cables that I played with:

• Stock Blu2 BNC cables (1m, free)
• Monoprice BNC cables (2m, $2.50 each) https://www.monoprice.com/product?p_id=626
• Canare BNC cables (2m) ($42/pair) https://smile.amazon.com/gp/product/B0010CIW98

With no ferrites on the BNC cables, here are the results from my listening tests:

2m Monoprice > 1m Blu2 stock cables (small but consistently noticeable difference)
2m Canare >? 2m Monoprice (*very* small difference, if any; hard to consistently pick up with all the cable swapping)

My take away: cable length matters more than build, with 2m better than the stock 1m cables, consistent with Rob’s recommendation from his listening tests.

Next, time to bring ferrites to the party. Here are the ferrites I used on my BNC cables:

• Wurth 74271633S 2.5GHz ferrites (preferred) (2x, $7 each) https://www.digikey.com/product-detail/en/wurth-electronics-inc/74271633S/732-1514-ND/1638918
• Wurth 74271131S 1GHz ferrites (8x, $5 each) https://www.digikey.com/product-detail/en/wurth-electronics-inc/74271131S/732-3625-ND/2901120

Rob has recommended the 2.5GHz as preferred (higher impedance in the RF range that matters for noise from the Blu2), but I had a mixed bag of 1GHz and 2.5GHz ferrites for these initial tests.

Given I could not detect a material difference between the cheap Monoprice cables and the Canare cables, I did my ferrite testing on the 2m Monoprice cables.

While playing music, I started to put ferrites on the BNC cables one pair at a time, starting at the DAVE end. I could hear a clear difference after 2 on each cable, with progressively less difference as I added the remain 8 ferrites (total of 5 on each cable).

Comparing the Monoprice 2m cables with 10 ferrites vs bare Canare 2m, Monoprice ferrited cables were the clear winner (not subtle).

So the Blu2 is a vector for digital noise (whether from a digital source connected to the USB input of the Blu2 or internal to the Blu2) to get injected into the DAVE. If you clean up the BNC digital link between the Blu2 and the DAVE, would that also clean up any noise being injected via USB? For this experiment I kept the ferrited-Monoprice-BNC cables connecting the Blu2 to the DAVE, and compared the 2m Tripp Lite USB cable + ferrites with the 2m Pangea USB cable (the really crappy one) with no ferrites. The result? They were very very close (close win for the Tripp Lite USB cable), so the answer seems to be “yes”.

One final experiment. DAVE is supposed to be immune to problems upstream of USB. What the heck is going on here? Taking Blu2 out of the equation and going with USB straight to DAVE, I tested the Tripp Lite USB+ferrite monster vs the stock Chord USB cable (no ferrites) vs my troublesome Pangea USB cable (no ferrites) connected straight to DAVE. To my ear, the Tripp Lite + ferrite cable and bundled stock USB cable were identical, with a VERY slight step down with the Pangea cable. DAVE takes care of business on its USB input. The challenge is USB injecting noise (via the Blu2) into the DAVE via the unisolated digital coax inputs on the DAVE, and the Blu2 injecting noise into the DAVE via those same inputs.

So let’s roll this all up. How does direct CD on the BluDave sound like compared to digital coming through the ferrite USB monster and the ferrite BNC monsters? To my ear, very very close (perhaps the slightest of edges to CD? Hard to say consistently).

Net net on my learnings from this digital tuning:

• Digital coax on the Chord stack (with no galvanic isolation on the Dave DX inputs and outputs) requires RF hygiene. Use reasonable quality 2m 75ohm coax cables (Monoprice is fine for me), add 4-5 of the 2.5GHz ferrites on the DAVE end, and Bob’s your uncle
• Your digital source is a potential source of noise injection into your Blu2 via USB. You’re fine to use a reasonable quality vanilla USB data cable.
• Audiophile USB cables that are trying to optimize signal transmission aren’t helping you when you’re trying to manage parasitic RF noise that is piggybacking on the digital connection (enhanced conductivity at the cost of additional RF noise is not helpful)
• If you like, you can load up the USB cable with 20-30 of the el cheapo ferrites if you really want to go the extra mile.

Net net for me? I just saved $5k on a new digital music streamer with some inexpensive USB and BNC cables, and an embarrassingly large number of ferrites. Thank you internets.

As I identify and address whatever the next big performance bottleneck is in my system, will my digital source become the performance limiter? Perhaps, but I’m delighted to be able to put off worrying about superclocks and ultra linear power supplies and modded network switches for a little while longer.

One last thing. How to do physical cable management once I cram everything back into my cabinet and these embarrassing cables are no longer cleaning laid out and isolated? For giggles, I got one of these https://smile.amazon.com/Kootek-Management-Concealer-Organizer-Reversible/dp/B01GCS77TU and wrapped the beast up. Hides my ferrite shame, and seems to be working for me so far.

Edit 1/21/18:

A quick (but very belated) promised update on Wurth 2.5GHz ferrites vs the 1GHz ferrites in my BluDAVE setup. I ordered a total of 10 of the 2.5GHz ferrites, and I was finally able to compare the two. I was able to hear a very slight but consistent improvement in detail and resolution (VERY slight) with the 2.5GHz ferrites over the 1GHz ferrites. Both were superior to no ferrites in my setup (for this test, Blu2 CD -> DAVE -> direct to Omega Super Alnico Monitors).

Is it worth swapping out 1GHz ferrites if you have them already? Up to you, but these are so (relatively) inexpensive that it is probably worth it for peace of mind, but not because it will alter the experience of the BluDAVE in any fundamental way. If you haven't ordered any ferrites, I recommend starting with the 2.5GHz ones.


Conclusion

The Blu recreates music with a true sense of reality that is fundamentally different than anything I’ve heard before. On the scale of “listening to music” to “experiencing a performance”, the emotional reality of what I’m hearing transcends even experiencing a performance to participating in a work of art.

For the best recordings, the experience of listening through BluDAVE is on the other side of some reality phase transition: my brain is no longer filling in the blanks and extrapolating, I am there with the artists and they are here with me, and I am feeling what they are feeling. The emotional impact of their art can be profound, and it is a gift beyond measure to make their art so profoundly manifest.

I will not be replacing my BluDAVE with a BluHugo2 (I am addicted to the BluDAVE sound), but the BluHugo2 is (remarkably) a huge step above the DAVE. As mScaler technology becomes more mainstream, it is fills me with awe to think these sorts of musical experiences will become available to ever larger audiences. I will also not be upgrading my digital server to something like the Innuos Zenith SE; with RF hygiene things are close enough to CD in my setup that I will be investing my energies in addressing other potential short comings in my system first.

More generally, the Blu2 has highlighted the limits of essentially all my content and equipment. Finding the right combination where any listening tests were not dominated by those limits was incredibly illuminating and humbling. Basically, everything degrades what the Blu2 can produce. You just try to minimize that degradation.

When you have a true ground truth reference in your system, I'm finding that I end up measuring everything else against how much it degrades from that reference. As someone who's ideal of criticism has always been to focus on how much something elevates, it has been a disorienting reorientation for me: eliminate as much as possible to try and approximate the true reference, then add things in to see how much they drag it down. I can't say I'm enjoying this new way of critiquing content and equipment, but it is shocking how clear differences and degradations are (this is non subtle stuff). There is no denying or penciling over the truth that you hear.

We are in early days of this brave new world, so there are some teething pains. A Chord future that depends on dual BNC cables to move around 705/768kHz signals between multiple pieces of high-powered digital kit will need some serious thought for how civilians are going to manage the sensitivity to cable placement and management and RF noise. Based on my experimentation and the reports of others, there is a clear opportunity to bundle cables that are optimized for this environment, and adding galvanic isolation to a future digital amp will also clean things up. Until then, good RF hygiene is required, so swallow your pride and load up on the ferrites.


Coda: The Emergence Of A Brave New World

Normally, I have done critical listening tests with headphones, but my (until now infinitely scalable) Sennheiser HD800’s have clearly topped out with the BluDAVE. The only configuration I have access to that exposes the real performance of BluDAVE is to drive high efficiency single driver Omega Super Alnico Monitors directly from BluDAVE.

To hear what the BluDAVE is capable of, I’ve had to eliminate as much as possible from the reproduction chain. Wow.

Anything between BluDAVE and the transducer degrades what you hear by some amount. Simple things like moving coax cables are audible. Adding one ferrite at a time is audible. Moving a power cord out of the way is audible. Any amplifier (class AB/D/T/tube/whatever) in the chain or speaker crossovers take precious transparency and presence away and is audible. I’ve resisted swapping out speaker cables and power cables for some esoteric $$$$ variety because I fear what my wallet will hear (ignorance is bliss), but I’m certain they will be audible and may be significantly. When Rob says that even the smallest XXX is audible in depth queues, he’s right.

This notion that anything between BluDAVE and the transducer degrades the reality of what you hear was a profound upside the head when I realized it. All my old tricks and nearly all my intuition were out the window. Seeking perfection and truth by stripping away everything but that perfection and truth. It’s enough to spur a mid life crisis.

So what does this new outlook mean for me in practice? We often talk about this or that piece of audio kit being “reference”, but that is in the context of what one is familiar with and that we compare everything else against. How are things better or worse? Same or different? Almost universally we speak of reference as a basis for comparison, to find common ground so we can understand something new in the context of what we know.

In a very first for me, the Blu2 is (for all practical purposes) a true reference: it establishes the ground truth from which everything else takes something away. That is, the Blu2 is a reference for measurement, not just comparison, and represents an ideal that everything else needs to work toward attaining.

Understanding what something is taking away is key to understanding and optimizing your chain, but it is humbling with the stark unassailable clarity about the differences that you hear. At least at the beginning of this new journey, I am hearing 50% to 80% changes (towards the ideal), not the usual 99.84 to 103.89% changes (vs the baseline reference) we endlessly debate about. It impacts everything from electronics to speakers to my room to my emotional mood to the actual music content and performance.

To be 35+ years into the serious audiophile thing (and even longer into the life thing) and to rediscover Beginners Mind in a ground truth is a wondrous and wonderful and profoundly humbling thing. I'm very grateful for the privilege and good fortune to have a piece of that mountain top in my living room. I am also exceedingly happy to celebrate the culmination of a lifetime’s work for Rob, who has been systematically working toward attainment of this ideal for over 30 years. Bravo sir.

For all this awesome, the mScaler technology in the Blu2 represents a true (truth?) end game for only one piece (albeit an incredibly important piece) of the music capture/transmission/reproduction chain. I can’t wait for hearing an absolute reference for digital music capture (Davina), the ability to drive more impactful transducers (digital amps), and an absolute reference for multi-driver and room correction (digital cross over), and for all these magical things to be tied together into a closed loop so that reality can be vividly and holographically reconstructed. It may take another 5-10 years, but we will hear reality fully captured and recreated in our lifetime, and the mScaler technology in the Blu2 is profound first pillar and foundation for the rest of that journey.

Disclaimer: The black Hugo2 unit described below was provided by Chord as part of a demo tour, in exchange for posting an honest review when I was done with the unit. The loaner unit has been returned to the tour organizers (thank you @Barra). No other consideration was given nor received.

UPDATE: I did not have my Blu2 in time for this review (I originally wanted to do a comprehensive review of the Chord Mojo to Hugo2 to DAVE to BluHugo2 to BluDAVE), but have since received it, and posted a second part to this review covering all things Blu. You can find it here: https://www.head-fi.org/showcase/chord-blu-mk-ii-digital-cd-transport.22848/reviews#review-19675

Background

After many years of life getting in the way of enjoying high fidelity music, a couple years ago I went through a process of upgrading my two channel system (documented here: http://thingssoimpossible.blogspot.com/2016/10/speaker-quest.html), then diving deep into headphones to be able to take that experience with me (documented here: https://www.head-fi.org/threads/adv...-head-first-into-the-head-fi-deep-end.824351/ )

After spending countless hours with delta sigma DACs of various levels (mostly with my Oppo HA-1) and R2R DACs (mainly Schiit DACs, all the way up to the Yggy), I saw a posting pointing to $400 Mojo’s on the German Amazon site (score!). In my initial research, it had come down to the Oppo HA-1 vs Mojo/Hugo, but I went with Oppo because the Chord DACs were so butt ugly (and didn’t have a remote, but the ugly part makes the story better). $400 was too good to pass up, so I jumped into the Chord world.

On first listen Mojo was awesome, but also disorientating for some reason. It took a couple weeks, but my brain adjusted to the Mojo to the point where it was very difficult to go back to my Oppo or my buddy's R2R DACs. I considered that my Red Pill moment, where I started to hear things in recorded music that I hadn’t heard before. Based on that promise, I ordered a Chord DAVE and preordered a Chord Blu2. Although my left brain was certain those would be good decisions, my right brain was nervous as hell until the DAVE arrived, and my left brain was proven right.

I’m now a convert to the Chord sound, and the intoxicating effect of what I call the Chord Magic: music feels real and physical, and the emotionality of the performance becomes tangible. How does the new Chord Hugo2 compare to its two siblings, and how best to capture and amplify that magic?


Philosophy

Unlike other audio components, I find it extremely difficult to audition DACs, and nearly impossible to do direct A/B comparisons across DAC signatures. For me, the DAC is a critical component in creating the synergy between source material to DAC to analog reproduction to your brain and how it bends and adapts to what it is hearing. It can take me weeks to really become part of the new system and understand what it evokes. If I focus on any particular detail with a particular DAC, unless the DAC is defective that detail will almost always be there in other DACs if you focus hard enough.

What matters for me is how the notes come together to something larger, a resonance that is greater than the sum of its parts. Once I hear that something special, I can look for words to describe it (transparency, clarity, etc), but I find it very difficult to listen for those things a priori. DACs are at that crucial pivot point between a recorded representation of the sounds, emotion, and artistry at a moment in time, and recreating those sounds, emotions, and artistry in a different time and place. In a very real sense, it becomes a proxy for the artist, and the new source of all those sounds, emotions, and artistry. When evaluating DACs, I need to let go of the left brain, and immerse myself in the sounds, emotion, and artistry as I would at a live performance.

As an imperfect analogy of that experience for me, mixing coal + chalk + water + iron filings in ever more precise proportions using ever more esoterically sourced materials won’t result in a child that you will cherish and adore and make the center of your life. Arguing about the purity of the water or where the coal was sourced from and the magnetic properties of the iron changes nothing. The real debate is how they come together, and how it comes alive and becomes meaningful for you.

The Mojo then DAVE have completely changed my experience of music. For the first time I've gone from “listening to music” to “participating in a performance”. Even with DAVE, different recordings evoke different levels of what I characterize as intoxication or euphoria from the performance. Classic recordings from the late 50s and early 60s in particular are remarkable with DAVE. They give a glimpse of transcending even “participating in a performance” to directly “experiencing an emotional truth” (what I think of as the art of the performance).

For me, this echos my experience of being delighted to happily listen to an amateur performance in a coffee shop or a subway that I wouldn’t in a million years listen to as recorded music (style or quality or content of music/performance); being in the presence of a real person expressing themselves through music is a magical thing. How close can you get to reproducing that emotional and artistic experience, and not just those noises?

Chord DACs are the best I’ve ever heard at crossing over from music to performance to even occasionally offering glimpses of emotional truths. I very much appreciate the opportunity to audition the Hugo2, and see where it sits on the spectrum between the Mojo and the DAVE. I was hoping to have my Chord Blu2 delivered in time for this review (to compare BluHugo2 vs BluDAVE), but that was not to be. When my Blu2 arrives, I will update this review with that comparison, with the sincere hope that it will take us even farther on that journey toward experiencing emotional truths.

As always, the chronicle of the journey is long. For those that want to jump to the end, I have a tl;dr section, and a story to sum it all up.


Hardware

Source setup:

• Macbook Pro and Mac Mini, running latest OS X, content on local SSD, running Roon 1.3
• Bit perfect either direct USB, or via direct ethernet to a Sonore Sonicoriber SE running Roon Bridge to USB, to the DAC

DAC setup

• Chord Mojo ($600)
• Chord Hugo2 (black tour loaner unit) ($2400)
• Chord Hugo2 (silver) ($2400)
• Chord DAVE ($13000)
• MIA: Chord Blu2 ($13000) (hopefully coming soon)

Headphone setup

• Sennheiser HD800 (with SR mod) ($800 used)

Traditional Two Channel Setup

• RCA from DAC to Benchmark AHB2 amp ($3000) to B&W 802D3’s ($22000/pair)

Direct Two Channel Setup

• RCA direct to Omega Super Alnico Monitors ($2000/pair)
• For Chord DAVE, XLR direct (in parallel) to JL Audio F112v2 subwoofer ($3700), tuned to room and low end fall off of Omegas (~45Hz)
• For Chord Hugo2, no connection to subwoofer

DAC settings

• For headphones, crossfeed set to 2 for DAVE and Hugo2 (no crossfeed setting on Mojo), unless recording is binaural (0 crossfeed)
• Neutral filter for Hugo2
• PCM+ mode, HF filter on for DAVE
• All DACs volume matched using a SPL meter
• For A/B/C DAC comparisons, I put all the DACs in the same Roon zone for synchronized playback and switched headphone from DAC to DAC

Tag alongs for fun

• Schiit Lyr 2 tube amp ($450) and Schiit Bifrost Multibit DAC ($600)
• Martin-Logan Motion LX16 speakers ($500/pair)
• Audio Zenith PMx2’s headphones (heavily modified Oppo PM-2’s) ($1800)
• Noble Katana CIEMs ($1600)
• MrSpeakers Aeon Flows headphones (closed) ($800)
• Grado HP1000 (HP2) legendary old skool headphones ($priceless)

Content

My Go-To Chord DAC Demo tracks and what I look for in each:

Pink Noise (mono), from “The Ultimate Headphone Demonstration Disc” bu David Chesky (Chesky, 24/192 FLAC)
Yeah, its pink noise, but it tells you a lot about a set of headphones as you get oriented to system. For 2 channel, great way to see if your speakers are aligned and you’re in the right spot. Great baseline reference to make sure things aren’t wonky and you’re in a good place (and it is sort of fun to think about all this technology being using to play a 24/192kHz noise file

Murakkaz Ah Ya Muddasin, from “The Splendour of Al Andalus” by Calamus (MA Recordings, DSD64)
Remarkable recording in what sounds to be a majestic and spiritual centuries old cathedral in Spain. With the right equipment, you are transported to a place you’ve never been to but always want to get back to. When the full group joins in, it is profoundly challenging to reproduce the mids and highs without sounding shrill and congested. When the reproduction is effortless, it is magical (to say the least…my jaw drops every time when it’s “right”) If the sound chain is able to maintain that glorious soundstage, it is off the charts. Todd Garfinkle is a magician behind the microphone.

Noche Maravillosa, from “Salterio” by Begonia Olavide (MA Recordings, 16/44.1 FLAC)
Another gem of a recording and performance from Todd. The precision and clarity of the instruments (particularly the percussive ones) is intoxicating and tangible.

Voglia Di Vita Uscir, fremo “Buenos Airers Madrigal” by La Chimera (MA Recordings, 16/44.1 FLAC)
Todd also is a master at capturing performances in a more orchestral setting. These performances by La Chimera are a joy.

Mahler: Symphony #2 'Resurrection’, 1st movement conducted by Iván Fischer (Channel Classics, DSD64)
Mahler: Symphony #2 'Resurrection’, 5th movement conducted by Iván Fischer (Channel Classics, DSD64)
Near perfect performance with a perfect recording. The dynamics and power of this performance are vivid and real: the orchestra virtually screams with one voice during the climaxes. This recording beautifully captures the essence of horns and low strings, which are very difficult to reproduce. The closest I’ve heard to the experience of the dynamics of a live orchestral performance.

Rimsky-Korsakoff: Scheherazade, 1st movement conducted by Fritz Reiner (Analogue Productions Remaster, DSD64)
The most perfect recording of the most perfect performance I’ve ever heard. Listening to this recording on a transparent system is a life changing experience: you are standing with Maestro Reiner in Chicago as his orchestra reaches for a performance for the ages. A cultural treasure, and worthy of building a world class system around.

Organ Prelude, JS Bach Magnificat by Dunedin Consort (Linn, DSD64)
Motet, JS Bach Magnificat by Dunedin Consort (Linn, DSD64)
A breathtakingly lovely recording! The dynamics and harmonics of the organ can range from a muddy “eh” to “holy crap!” depending on the quality of the reproduction. Standing in the middle of choir is a lovely test of imaging and voice reproduction: the more precise the soundstage the more you can pick out individuals (including depth and height…remarkable).

Handel: Messiah - Chorus. O thou tallest good tidings by Dunedin Consort (Linn, DSD64)
Handel: Messiah - Hallelujah by Dunedin Consort (Linn, SACD)
A magnificent recording, reconstructing the original version of Handel’s Messiah, with a total of 12 singers. The normal complexity of the piece is captured in a way where you can hear each voice in the chorus, and how it comes together into a larger whole. An amazingly intimate performance when the reproduction chain can manage the complexity and dynamics and not have the soundstage become muddy and flat.

Arnesen: Magnificat - Fecit potentiam by TrondheimSolistene (2l, 24/192 FLAC)
This is such a lovely recording at any quality level, but goes from incredible to other worldly as the chain scales up. The orchestra, choir, and church should all have equal contribution to something far greater than the sum of its parts. When it all comes together, you can feel the three core elements feeding off each, creating a profound joy that is sweeps you into euphoria.

Stardust, from “Duets” by Rob Wasserman (16/44.1 lossless)
Every track on this album is a gem, but this one is particular is a fantastic test of sound stage and imaging. At its best, you hear each backing voice precisely in space, but still presenting as a harmonious whole. In real life, detail and precision spatial placement isn’t hard and clinical, why should it be in reproduction?

Oh, Lady Be Good, from Bassface Swing Trio Tribute To Cole Porter (DSD64)
Night and Day, from Bassface Swing Trio Tribute to Gershwin (DSD64)
These direct to disc Stockfisch recordings are extraordinary. Imaging and dynamics FTW. Recordings like these are why we obsess over the things we obsess about. I’m looking to get lost in the music, and the band appearing to be sitting right there. When tonal balance is just right, these performances just jump off the SACD.

Shamas-Ud-Doha Bader-Ud-Doja, from “Shahen-Shah” by Nusrat Fateh Ali Khan (16/44.1 lossless)
The first track from what was my surprise 2012 album of the year (see http://thingssoimpossible.blogspot.com/2012/12/2012-albums-of-year.html for that backstory, with the surprise ending). A remarkable supremely spiritual performance by a remarkable man, captured in an “eh” recording. The question for me is what these DACs can do to elevate a middle of the road recording that is worthy of elevation.

Let Me Touch You For Awhile, from “Live” by Alison Krauss (DSD64)
I adore Alison Krauss. Having equipment that can reproduce the wonderful emotion and musicality of these amazing artists is why I spend so much time looking for the right speakers/cans/etc. Their Live album is special, and you can feel the humanity and emotion in this track.

Tenderly, from “While She Sleeps” by Art Lande (Blue Coast, 24/88.2 FLAC)
Cookie Marcenco has a gift for capturing piano, guitar, and voice as if you’re sitting in the room with the artist. If you’ve ever sat next to a wonderfully tuned piano with an extraordinary player, you know how magical that experience can be. The best pianos sing with resonances that envelop you. The best musicians know how to coax beauty and life out of the instrument. This recording from Art Lande captures that magic. The stronger the dynamics, soundstage, and precision of the system, the more lifelike this track becomes for me. I haven’t experienced this track topping out: the better the reproduction chain, the more lifelike it becomes.

One World, from “Session 1” by Sareena Overwater (Blue Coast, DSD64)
One World (Instrumental), from “Session 2” by Sareena Overwater (Blue Coast, DSD64)
Real magic from Cookie. These tracks are wired directly to deeply held memories for me, and the stronger the reproduction chain, the stronger the emotion that they evoke. There are better examples of piano performance and better examples of vocals, but the emotional truth and power of this performance is unmatched. More on this track at the end of this review.

99, from “Blue Coast Special Event 43” by Meghan Andrews (Blue Coast, 16/44.1 FLAC)
Cookie knows how to record guitar too, and Meghan Andrews knows how to bring a performance that is worth catching in a bottle.

Vous et Moi, from “Night and Day” by Willie Nelson (SurroundedBy Entertainment, 24/96 FLAC)
What if Willie Nelson was in a dispute with his label, got pissed off, and invited the best musicians he knew to the studio to record an instrumental album in full surround? Yeah, this actually happened, and it is as awesome as you think it is. The album is amazing in a musical surround setup, but a proper 2 channel system puts you right in the middle of the band. Incredible stuff.

Music in My Room, from “The Folkscene Collection, Vol. 3” by Cheryl Williams (Redhouse Records, 16/44.1 FLAC)
We’ve all had the experience of being in a coffee shop or small venue, when someone with a guitar and something that has to be shared commands the attention of everyone in the room, and you have a moment where the whole room is one. These CDs where engineer Peter Cutler captured intimate in studio performances at KPFK in Los Angeles are replete with those moments, but this performance by Cheryl Williams stands out for me. With a great reproduction chain, the guitar is real and present, and the voice and singer connect at a deep emotional level. A jewel of a moment, waiting for the right equipment to be a moment again.

All I Want, from “After Blue” by Tierney Sutton (BFM Jazz, 16/44.1 FLAC)
Tierney Sutton has a striking clear and present vocal style, and that is on full display on her “After Blue” album of Joni Mitchell standards. I continue to be amazed how ever better DACs extract ever more nuance and subtly of performance from top tier vocalists. It is a joy to hear the depth of craft and art of vocal performance on tracks like this.

Rosa fresca, from “Il viaggio d’amore” by Arianna Savall and Petter Udland Johansen (Carpe Diem, 16/44.1 TIDAL Lossless)
“The journey of love” is a marvelous exploration of love through the ages, from multiple cultures and times. The whole album is a joyous wonder, but the opening track (“Fresh Rose”) of a traditional song from the 1500s is an invitation to join in joy and unbounded hope. The company of players is feeling it, and you do too. When you’re hearing every string pluck in the strums and the voices comes together into something much larger than the sum of its parts, you’ll be glad you accepted that invitation.

L’Amor, from “Bella Terra” by Arianno Savall (Alia Vox, 16/44.1 FLAC)
If “Rosa fresca” makes you fall in love with Arianna Savall singing about love, you’ll want to seek out her “Bella Terra” album. An accomplished harpist and vocalist, Savall is at her best when she brings both together: voice and instrument are one, and evoke marvelous sound and emotional resonances in each other.

Traveler, from “Little Crimes” by Melissa Menago (Chesky, Binaural 24/192 FLAC)
Airplane, from “Little Crimes” by Melissa Menago (Chesky, Binaural 24/192 FLAC)
A gem of a recording from Chesky: direct binaural recording, made in a church while it is raining outside. Like all Chesky binaural recordings, you are there sitting with the performers (Airplane), with special magic from the sound of the rain outside of the church (Traveler). Fantastic test of soundstage and spatial detail.

Hold On, from “Sessions from the 17th Ward” by Amber Rubarth (Chesky, Binaural 24/192 FLAC)
Don’t You, from “Sessions from the 17th Ward” by Amber Rubarth (Chesky, Binaural 24/192 FLAC)
More Chesky magic. No rain this time, but Amber’s rich voice + violin + guitar + percussion are amazing on any system, but the sense of being there scales beautifully as the reproduction chain improves (it is magical when your system crosses some threshold of transparency…all of a sudden you are there).

Stuck In A Moment You Can’t Get Out Of, from “Open Your Ears” by The Persuasians (Chesky, Binaural 24/96 FLAC)
One last gem from Chesky. There is a profound difference to listening to a recording of a group of people sing, and being with a group of people that are singing. This is another recording that (at least for me), when you cross some magical threshold of transparency, the people become real.

Karamawari, from “Gamushara” by YAMATO the drummers (TIDAL MP3)
Drums are notoriously difficult to reproduce in the way you experience them in person. There is a physicality that is lost in most systems. Hearing a group of percussion masters really bring it on a system that can approximate that in person experience? Amazing.

Get Lucky, from “Random Access Memories” by Daft Punk (24/88.2 FLAC)
Another track that transcends pop when played back through equipment that really reproduces the full range and dynamics of the recording. The subtlety and layers on Nile Rodgers’ guitar work is incredible, and the recording is outstanding so you should be able hear it all. I listen for whether it is washed out, and how well I hear all the (considerable) nuances in his playing.

Take Five, from “Time Out” by Dave Brubeck (Analogue Productions SACD)
An excellent test of dynamics at the high end. As an aside, these Analogue Productions remasters are off the charts!

No Love Dying, from “Liquid Spirit” by Gregory Porter (24/192 flac)
Another lovely recording and performance, that on a balanced system hits a resonance that is next level for me (just sounds “right” and get the “wow!”) When things are not in balance or boomy/shrill, I hear it loud and clear.

Beethoven: Symphony #9, 4th movement by Suitner (OG Denon, 16/44.1 lossless)
This was the first CD I ever bought in 1984 (first CD ever made?) I know every second of this movement and every nuance. My current 2 channel setup was the first time I had ever heard the entire movement without a break (every other system I’d ever had/auditioned had some break at some challenging passage).

So What, from “Kind of Blue” by Miles Davis (Japanese single layer SACD version)
One of the finest recordings and performances of the 20th century. Always the last track I play during any audition. Until there is a time machine to take me back to March 2 and April 22 1959, I will buy every new remaster of this album, and play it on every piece of high end audio kit I can find.



Physical Impressions

Yeah, our listening session was a bit out of control (see photo above). From left to right, you have a lovely Scott Radke marionette, my JL Audio F112v2 sub, my beloved B&W 802d3 speakers, Omega Super Alnico Monitors (with some $100 speakers I forgot about sitting on top), Martin-Logan Motion LX16’s, a buddy's Silver Hugo2, a buddy's modest Schiit stack (Lyr2 amp + Bifrost multibit DAC), Black Hugo2 (tour loaner), and my Black Mojo. Heading down, you have my Chord DAVE (with Sonicorbiter SE hiding behind it) and my Benchmark AHB2 amp.

The Hugo2 is (physically) a mixed bag. It was much lighter than I expected (esp. after the Mojo) while still feeling very robust, but the sharp corners seem unnecessary. As a transportable, you’d definitely want a case to protect the unit and protect everything else in your bag. The weight of the Hugo2 was also surprisingly reasonable (esp. compared to that mini tank that is the Mojo). It could easily be an everyday carry device.

Having the silver and black Hugo2 side by side, both were very nice. Chord did a lovely job with the finish on the silver unit, exuding a refined sense of quality and depth. The black is consistent with what I have on my Mojo and DAVE, and my preference to keep everything in the family. I think most people would be delighted with either finish.

I was shocked at how horrifically bad the button/light design/scheme was for the unit. Any modern device where you have to study the instructions and fiddle with garish buttons and obscure color schemes to figure out what the hell is going on has taken designer affectation way too far. The only saving grace was that I had a clear favorite filter (so I could ignore that button), only used USB input (so I could ignore that one), and cross feed has such an obvious sonic impact that it is hard to screw up what setting you’re on. As frustrating as the button/light scheme is, the remote makes everything better. Keep it close and keep your sanity.


Listening Impressions: Headphones

Lets start with the most important question, and settle the debate that has been raging: Silver Hugo2 vs Black Hugo2?

After 40+ hours (maybe it was seconds) of critical listening, I can definitively state that they sound the same (sorry @doody

With headphones, the comparison between the Mojo, Hugo2, and DAVE is much more interesting. What does each 5x step in price at each level buy you?

I went through my full song list, switching back and forth between the three sibling DACs (see end for my detail notes/impressions). The differences were clear and consistent, regardless of track/genre/etc.

Mojo was very satisfying, and created a better listening experience than almost any other non-Chord DAC I’ve heard, but it only hints at the sense of euphoria and emotional engagement I get from the Chord DAVE and Hugo2. I consider it the best value DAC available anywhere, even up to 5x its price, but the danger is you hear that “something more” and your brain gets that rush of being in front of real musicians, and all sense of fiscal control goes out the window (guilty as charged).

With the Hugo2, those hints of clarity/reality become sustained. Spatial resolution goes WAY up, and individual instruments and people become much more resolved and distinct. Phrasing (vocal and instrumental) becomes vivid, and the musicality and emotion of the performance goes next level. An incredibly emotionally satisfying sense of presence at the performance, and a window into the artistry of the musicians.

With the DAVE, what the Hugo2 does so well goes off the charts. For me, this is the musical crack, tapping right into the emotional centers of my brain. Whereas with the Hugo2 I can hear individuals and their performances really for the first time, with the DAVE I get a vivid sense of how they are feeding off each other and the space they are performing in. Mesmerizing and enthralling, and emotionally vivid. This is an experience I never thought was possible with reproduced music, and like any good junkie, I want more MORE MORE. I can’t wait to hear what the Blu2 will bring to the party.

Some quick summarized impressions from headphone listening:

• Mojo is better with crossfade, even if no longer bit perfect (bite the bullet and set up the filter in your playback software)
• Musical congestion (large scale orchestral pieces, etc) really challenges resolution on the Hugo2, but is revelatory when a DAC like the DAVE can keep up (so much power in groups of people expressing music together)
• As you go up the stack, there is a big difference for nuances in vocals, strings, drums, etc. The artistry really becomes palpable
• Resonances and ambient reflections make a big difference for reality and balance. Space and mix get so much more natural as you move up the stack
• The nuance of vocals and performance in a group setting is startling when you are able to start hearing it. I've changed my music listening mix to include far more choral and orchestral pieces than I ever listened to before (from <1% to maybe 40% now)

On my non-scientific impression scale of 1-10, calibrated so the Mojo was at the low end and DAVE at the high end so it is easier to see where the Hugo2 lands in between, the Mojo came in around a 2, the Hugo2 a 4, and the DAVE around an 8. Interestingly, this is close to the ratio of additional bits of temporal resolution as you go up the Chord stack (+1 bit from Mojo to Hugo2, +1 1/2 bits from Hugo2 to DAVE)

On this scale, almost any other DAC I’ve heard wouldn’t even get above 0. Rob’s DACs are in a league of their own. Within the Chord stack, the differences are not subtle, the experience fundamentally different and better, crossing some sort of phase transition from listening to music to being part of a performance. Great stuff, and I can’t wait to hear what the next +2 1/2 bits that the Blu2 gives us.


Listening Impressions: Traditional Two Channel

My perception of what I think of as the Chord Magic is more subtle in my traditional two channel setup. Like most things I’ve experienced with these kinds of high end system, you can move the needle in obvious ways, but very difficult to get transformational changes.

As I went from Mojo to Hugo2 to DAVE, there was progressively more richness and reality, and I know enough of what the rush from that Magic felt like that I’m able to find it easier and easier as you go up the ladder. However, you do need to listen for it, rather that it overwhelming you like the headphone experience.

That being said, this was with the Benchmark amp, which is a particularly fast/low distortion/low noise amp (to say the least). With the Schiit Lyr2 tube amp, the Chord magic was basically gone.

I’m fairly certain that a fundamental transformation of the traditional two channel listening experience will need to wait until Rob’s digital amp becomes available. I’m very eager to hear what my B&Ws can do once the digital amp becomes available.


Listening Impressions: Direct Two Channel

Based on Roy’s (@romaz) recommendation, I’ve long been intrigued about connecting the DAVE direct to a high efficiency single driver speaker like the Omega Super Alnico Monitors. If you can eliminate the power amp and the cross overs and the imbalance between different speaker drivers, could this be close to the ultimate two channel experience?

For this eval, I ordered a set of Omega Super Alnico Monitors (thank you Louis!) so we could try them in a traditional 2 channel setup (DAC to amp to speaker) and direct from the DAVE and Hugo2. During our listening tests, we also discovered the marvel that is near field listening with these single driver speakers. For kicks, we also did listening tests with the Martin Logans (high efficiency multi driver speakers with what should be a fast a ribbon tweeter)

Starting with the Martin Logans, the traditional two channel experience was OK for what you would expect for a modest bookshelf speaker (nothing special here). The Hugo2 (~1W) wasn’t beefy enough to drive them direct, but the DAVE (~2W) was. In far field, imaging was very limited and at best OK. I had zero sense of depth, and very limited spatial resolutions (maybe 4 distinguishable zones, and virtually no height). Dynamics were muffled, with no pop or attack. In general, playback was smeared, with limited detail. Piano sounded like a recorded piano, not a real piano. I’d give it maybe 1/10 (for the price) even driven directly from the DAVE. Not an auspicious start to our experiment.

Near field with the Martin Logans direct from the DAVE was a much better experience. Imaging may have improved to maybe 8 zones, but still no depth. For complex orchestral pieces, the soundstage collapse to seem like it was coming from two speakers. The speakers also lost musicality at low volumes. Maybe 4/10 (for the price). Better, but at best incremental and not transformative.

Net net: the Martin Logans are OK mid to low end bookshelf speakers, and except for brief flashes can’t keep up with the Chord kit, and can’t recreate that Chord Magic. Big miss.

On to the Omegas. With single drivers (no cross over, no concerns about matching the tweeter with the mid/bass driver, etc), and fast and responsive Alnico magnets with a low mass cone, we should get near perfect phase alignment between the channels. So how do the Omegas do? The Omegas were a completely different experience, and one of the finest experiences of music reproduction I’ve ever experienced and enjoyed.

Driving the Omega’s in traditional two channel setup (DAVE to amp to speaker) was incredible: vivid imaging, ultra fast and effortless highs, with amazing spatial resolution. Good resolution for height and depth, and a real physicality for things like horns and strings. The bass extension was surprisingly rich and deep, and highly musical. You can get away without a sub, but the right sub (fast enough to keep up with the Omegas and low distortion) adds that something extra that takes it over the top. Piano now sounds like a real piano, and you can close your eyes and see where people are standing in the choir. Let’s call it 7/10 (for the price, even though the Omegas are 4x the price of the Martin Logans)

Listening to the Omegas near field in a traditional two channel set up was next level again: depth and height imaging became fantastic, with a much more spatially balanced soundstage (esp. for more complex orchestral pieces). The musicality was preserved whether at loud volumes or extremely low volumes (amazing). Left right resolution is excellent, up down OK, and depth resolution very coarse (but it is there). Piano even more real, and voices the same. Call it 9/10 for price. An incredible two channel experience, well beyond anything I had ever experienced before getting the Chord DACs.

With all that, the real revelatory experience was going direct from the DAVE to the Omegas. In far field, soundstage becomes massive (all dimensions) and precise. Scheherazade is everything you dream it to be…you can almost hear individual instruments (almost), violin is angelic and soaring, and you can look in an arc around the orchestra like you’re standing in the conductors spot. Choral recordings cross into real territory, where you don’t have to use your imagination to imagine what the setting was like. Strings much more precise and real, and Stardust is a wonder…the vibrations on the bass are distinct and blend with the voice marvelously (interestingly, the precision of the bass vibrations makes the bass sound like it goes deeper). Much better depth resolution, and height resolution, and piano takes me back to sitting next to a real piano as my daughter is playing it. Cheryl Wheeler on guitar is that coffee shop experience (the humming of the guitar strings is what it sounds like on my guitar). 100/10 for the price…absolutely incredible and an experience that you must seek out.

As incredible as DAVE direct to Omegas is, listening to them in near field takes it to a completely different level: INSANE imaging, depth, height, evenness of soundstage…it is a real world stage. Everything that was awesome in far field made more incredible by the depth and vividness of the soundstage. The low volume musicality is off the charts….you can hear everything and lose no musicality by losing volume. 200/10 for the price. I am restructuring my living room so I can have this experience going forward.

Omega’s driven directly by the DAVE is (without hyperbole) among the finest music listening experience (reproduced or live) I’ve ever experienced. If this is any indication of what we can expect with Rob’s digital amp is available, I am grateful to still have the hearing to be able to appreciate something this amazing.

So what about the Hugo2? Can that tiny little box with <1W output touch that magical experience of driving Omegas directly from the desktop DAVE with its <2W of output? Incredibly, the answer is a definitive yes (with some notable asterisks).

First of all, it is otherworldly to hook up a Hugo2 direct to speakers and hear that kind of volume and music from a tiny portable. It seems like magic and an impossible thing emanating from that tiny box, but you can drive extremely satisfying music levels direct from the Hugo2. The experience is very reminiscent of the DAVE direct experience, but a similar step down as what I heard from the DAVE to Hugo2 with headphones. In this case, going from 100/10 to 50/10 far field, and 200/10 to 100/10 near field is a wonderful first world problem to have to deal with. In the right circumstances, Hugo2 driving the Omega Super Alnico Monitors is dollar for dollar the best musical experience I’ve ever had.

So what are the asterisks and right circumstances and all the caveats clouding the last paragraphs? For less complex pieces, like vocal, small jazz ensembles, etc, this is an ideal pairing. Make sure to be careful to adjust volumes for different albums that are mastered to different levels, since it is easy to over push the Hugo2 and start get some harshness (esp. in far field…in near field with comfortable listening levels, I never had to worry about it). With more complex pieces (orchestral pieces or pieces with driving bass or trashing hard rock), you lose the magic quickly: things just collapse back to “normal” (a very nice normal, but the magic is gone). The poor Hugo2 has limits on the complexity and dynamics it can drive on the Omegas vs what the DAVE can do.

If this is the path you’re going, I would drive direct Hugo2 to Omegas as much as possible, even if it means changing what you listen to. For pieces that overwhelm the Hugo2, get a nice baby amp like the Temple Audio Bantam Gold and swap it in when you want to rock the house, or spin up a large scale orchestral piece. Yeah, swapping wiring is a pain, but you’ll be very very happy. If you can swing the extra expense for DAVE, you’ll be happier still, esp. how amazing large scale orchestral pieces are with the DAVE direct to the Omegas.

For those use to full range two channel setups like mine, what does this mean for you? If you have a highly musical sub (like my JL Audio) that is fast enough to keep up with the Chord kit, low distortion, etc., you’re left with a very very hard choice. The combo of DAVE direct to the Omegas and JL Audio (via DAVE XLR outputs) is breathtaking. Do I really need full range $20k speakers and all the goodies/baggage that come with them?

(Note: I did not try to drive the Omegas and sub directly from the Hugo2, so I can’t speak to whether that impacts how far you can push the Hugo2)

For now, I’m structuring my living room to have a “Direct Chord/Omega” zone, and a separate traditional two channel zone (B&Ws, Benchmark, etc), and waiting to hear how Rob’s work with his digital amp progresses. If Rob can even approximate what I’m hearing from the Omegas direct through the B&Ws, that will be an amazing experience. I can’t wait to see where this goes.

If/when I again have a private office at work, the headphones will get put away and I’ll have some Omegas on my desk in a near field configurations, being driven by a Hugo2. Until then, I’ll be using my close Aeons, driven by my Mojo (pending an upgrade to a Hugo2 once I sort out what the BluHugo2 brings to the party).


Listening Impressions: Scaling headphones with Chord DACs

I did the bulk of my critical headphone listening tests with my Sennheiser HD-800’s (with the SR mod), which I know well and scale nicely with my DAVE. But what about other headphones? How do they scale with the Chord Magic as you go from the Mojo to the Hugo2 to the DAVE?

For this test, I did a matrix comparing AudioQuest Nighthawks to MrSpeaker Aeon Flows (closed) to AudioZenith PMx2’s (modified Oppo PM-2’s) to Sennheister HD-800’s (with SR mod) to Noble Katana custom in ear monitors to a vintage set of Grado HP1000's. I did not evaluate which headphones are best from the usual criteria of tonality, distortion, etc (that is highly subjective, with different tonal signatures appealing to different people). Rather, I listened very closely for that unique Chord Magic of resolution and speed and musicality and physicality. Which cans were able to express the extra Chord awesome sauce as you go up the Chord stack?

To my ear, the Sennheisers were the best (consistent with my experience with my DAVE) with a surprising close second place going to the Aeon Flows. Katanas came in a bit behind, then the Grados, Nighthawks and PM-x2’s. Since Rob uses the Nighthawks in his development of these DACs, that was a surprise to me.

For the Mojo and Hugo2, there were differences, but all the cans were very close. It wasn’t until you got to the DAVE where the differences were more pronounced. I suspect that the Blu2 will do more to help find out where these cans top out.

Based on this test, I am motivated to sample some of the other TOTL cans. If there is anybody in the San Diego area with Hifiman HE-1000 v2’s or other cans that are well matched to Chord kit, drop me a note and we can try to set up a listening session.


tl;dr

• Source material matters. Try to get as close to expertly mic’ed and minimal mixing as you can, and avoid compression like the plague. High res content is a bonus, but the Hugo2 elevated traditional redbook to high res levels (including lossless TIDAL streaming). Since getting my Chord DAVE, I don’t purchase high res music anymore, and the same applies to the Hugo2.
• Hugo2 is surprisingly light, but really needs a case to avoid cutting up things. Definitely transportable, and portable for the committed.
• Hugo2 delivers more of the Chord magic than the Mojo (at 5x the price), but not in the same league as the DAVE (at 5x cheaper). The differences are not subtle, but you’re going from very good to great to world class awesome.
• Going direct from the Hugo2 or DAVE to high efficiency single driver speakers like the Omega Super Alnico Monitors is a revelation, and everyone owes it to themselves to find a way to hear these things…wow!
• There is not quite enough oomph in the Hugo2 amp to direct drive the Omegas for complex music (how amazing would that have been?), but a remarkable experience at modest volume levels and more intimate music. One of the best dollar for dollar musical experiences I’ve ever had.
• It takes surprisingly little of the suboptimal or wrong stuff (Martin Logan speaker, Schiit Lyr2 amp, etc) between the Chord kit and your ears to completely kill the magic. It takes very little for things to collapse back to normal (a very nice version of normal, but no longer transcendent). Minimize everything you can between the output of the Chord DAC and your ears. The more you can eliminate and more you can simplify or lighten, the more the Chord magic can shine through.
• In theory BluHugo2 and BluDAVE should be very close in audio quality, but I can’t test that theory yet. If that theory works out, a reasonable play would be to put the money you would put into a DAVE into a Blu2 to go with a Hugo2. Stay tuned.
• For those that have already taken the red pill, the Hugo2 a VERY worthy upgrade to your Mojo, and a great approximation of the DAVE at the office and when out and about. For those that haven’t taken the red pill yet, grab a Mojo if you’re nervous if the hype is real. If you like the hints of what you’re hearing, you’ll love the Hugo2.
• Headphone experience can't touch the experience of DAVE and Hugo2 direct to Omegas (not even in the same zip code, with even Sennheisers….TBD if other headphones can close that gap, but these are the best Chord Magic headphones I have right now)
• Winner scenario for sane people is Hugo2 direct to Omegas in near field, with a reasonable amp like the Bantam Gold as a stop gap when listening to more complex/dynamic music. Add a fast musical sub like JL Audio F110 to fill out the bottom and be in awe of what you’re hearing. Down the road, dive into Blu2 and Rob’s digital amp once that dust settles and cost gets better.

A closing story

I’ve shared this story publicly and privately to Rob and Cookie before, but I wanted to share it here to give a sense of why I care about this stuff and what it means for me.

Earlier I mentioned how Sareena Overwater’s “One World” (Blue Coast Records) is wired directly to startingly deep emotions for me. When I listen to it, I’m taken back more than a decade. My older daughter is in college now, but when she was younger she was a very serious pianist. As she began to blossom as a musician (around age 8), we needed to upgrade from our ratty console piano to something more appropriate.

After 6 months or so of looking, I found a used 1924 Steinway in Rhode Island that looked perfect. The woman who owned it had received it new as a gift from her parents when she was around age 8, but no longer had room for it as she moved into the final phases of her life. A miraculous instrument, maintained and played with love. My daughter was and is the second owner, and I am hopeful she too will be able to enjoy it for many decades to come, and pass it to some deserving musician when it is her time to do so.

I spent countless hours lost in the sound of my daughter playing that piano, and know the sound and feeling of that vintage Steinway in my DNA. Cookie Marcenco also has a vintage Steinway in her studio at Blue Coast Records, and she is the most gifted person I’ve ever heard at recording piano. With the Chord DACs, I listen to recordings of Cookie's vintage Steinway, and with some of her musicians I have the visceral experience of going into a time machine and hearing my daughter play piano all over again. It is like catching a smell or hearing something that instantly transports you back to your mothers kitchen: the emotional connection is intense and overwhelming, and the closest I can be to experiencing my daughter's music now that she's at college. The feeling and emotion of my daughter playing her piano is made real in Cookie’s recordings.

My daughters piano is in long term storage, waiting for the day she has her own place and is able to enjoy making music with it again. While I can’t wait to hear her play again, I am grateful to be able to enjoy the echoes and evocations from Cookie’s studio, via Rob’s DACs.

When I first listened to this song (which I knew well and loved as a song) with my Mojo, I felt glimpses of reality in this song and felt the emotional presence of my daughter. It persuaded me to order a DAVE sight unseen, reaching out for that completely unexpected hint that I had felt in the music. Listening to this song with my DAVE, I am overwhelmed with emotion and end up weeping every single time. With Hugo2, while not as intense as with the DAVE, the emotion and sense of connection is very real, and I am swept away in memories and a sense of overwhelming love and pride for my daughter.

Can I put a finger on what combination of timing and taps and noise floor modulation and voodoo and whatever else can take a piece of well known recorded music and turns it into an emotional time machine that brings me to my knees every damn time? I can't, but I am enormously grateful to feel the presence of my daughter and her piano again. An unexpected and precious gift that was hidden in the music all along, without me knowing it was there. Thank you Sareena, Rob, and Cookie for helping me find that emotional connection all over again.



APPENDIX: Detailed Ratings and Notes

Note: these ratings are calibrated so that Mojo is on the low end and DAVE on the high end, so it is easier to see where the Hugo2 falls in between them.