JDS Labs Atom Amp+ Hevi

The JDS Labs Atom Amp+ Hevi is a cool entry-level headphone amp, proudly made in the USA. It's got a bit more weight than its predecessor. You can snag it for just $114.​

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Introduction to the JDS Labs Atom Amp+ Hevi review​

Hi-Fi audio gear is getting better and cheaper through the years. Stuff that was ultra high-end like 10 years ago, now has really strong competition at a fraction of the price. This competition comes particularly from China, but there are also a couple of companies from other parts of the world, and JDS Labs is one from the USA. They deliver audio gear with awesome specs at an exceptional value. Their approach involves creating straightforward, meticulously designed devices that offer exceptional specifications within their class, or even beyond.
I really love the approach of JDS Labs, they are making audio gear without any marketing bs. Even on the Atom Amp+ product page, they wrote that the amplifier has “only” 1W of power because they wanted to avoid the marketing race. Additionally, they are running a blog where you can follow their latest releases. What’s important yet again, there is no marketing boilerplate, only the spirit. You can read some technical details and what’s the difference between older models and the released ones without unnecessary eloquence.

Packaging, Build Quality and Tech​

The paragraph about the packaging is quite tough for me in this review, because sometimes I’m writing that the package is simple, nothing fancy, just a box with some foam and some stuff inside, but JDS did some steps further the Atom Amp+ Hevi arrives in black cardboard, with a power brick in another one and that’s it. They had to cut some corners and you can easily see that the money was spent elsewhere.
In terms of build quality, I can write something more, Atom Amp+ Hevi is $15 more expensive than the OG Atom Amp+ and the only difference between these two devices is the material of the enclosure and the knob. The new version of the amp feels more rigid and feels better made thanks to the use of aluminum instead of plastic. What’s most important is that the circuit board stays the same, so no matter if you choose the standard or Hevi version, the performance stays the same. On the backplate of the amp, you will find two inputs – an RCA and a 3.5 mm jack, and an RCA preamp output. Additionally, there is a power barrel jack and that’s all. On the front, there are two switches for gain and input, a volume knob, which is a power switch at the same time, and a 6.3 mm jack which is a headphone output.



As I’ve already mentioned, the inner construction is exactly the same as the construction of Atom Amp+, so it’s a standard headphone amp construction – an opamp-driven LME49600 current buffer. It provides low output impedance, so I could drive Craft Ears Aurum without any issues, with very low distortion and noise, and good power output – 1W RMS at 32 Ohm. The manufacturer claims that the power is limited because they wanted to keep the power supply reasonably sized and to be honest Atom Amp+ Hevi can easily drive most of the headphones in the market, but I will check these claims later.
Overall, while it’s still not rock-solid and super heavy, I’d definitely call it an upgrade over the original Amp+. Most importantly, the price difference is rather subtle and it’s going to be an easy decision for everyone considering buying a JDS Labs amp.

How does the JDS Labs Atom Amp+ Hevi sound?​

This part of the review is a tough one because since it’s the same construction as the classic Atom Amp+, Michał has already written everything about the sound of the Atom stack in his review. But let me try to describe the headphone amplifier only, maybe we will discover something new. It’s a headphone amplifier with a sound signature quite popular among budget-fi gear – neutral with a little warmth and a good bass.
A thing that really pops up is that the Atom Amp+ has a serious amount of power, it can easily drive AKG K712, but it also can handle HiFiMAN Arya Organic, or what’s even more impressive Sennheiser HD8XX. Maybe it lacks on many fronts when compared to e.g. my daily driver – Topping A90, but when you remember that the reviewed JDS Labs Atom Amp+ Hevi costs just $114, then you will probably have the same thoughts as me – it’s a budget killer.
Let’s start with the bass response. As I would expect from a solid state amplifier the bass is fast and responsive. It’s not too heavy, but you won’t complain that it’s thin or recessed. It’s balanced but on a warm-ish side with a solid sub-bass punch and pleasant, nicely textured upper bass. To be honest for me It’s the best part of the sound signature, I love to listen to some electronic music with it.

The way the bass hits in Veridis Quo by Daft Punk is just great – it’s very unconstrained and easy, but at the same time it isn’t muddy or soft. It can slam when it’s necessary, but on the other hand, it can be light and easy to assimilate as well. What’s important to point out is that HiFiMAN Arya Organic has really good bass, but it requires loads of power to make it sound fully and rich. JDS Atom Amp+ Hevi can easily provide that amount of power.
The midrange is balanced as well, it lacks the lower midrange a bit so male vocals are slightly faded, but every time I’m complaining about something I’m reminding myself it’s the price – like you can buy a headphone amp that has some down sights, but overall it’s a pretty well-performing device, or you can get five to six vinyl LPs. After this recall, I can easily tune a blind eye to the minor flaws I just mentioned. The upper midrange is definitely better exposed, but it still lacks the definition of female voices.

Another thing I’m lacking is the texture. For some people the smooth sound is good, but I like when Imelda’s May vocal in 11 Past the Hour rips skin off my ears, this causes me to feel the sound is engaging. Overall for me, the midrange is the most boring part of the sound of JDS Labs Atom Amp+ Hevi. What’s important don’t get me wrong, mids are very correct, but this correctness and the stillness make the sound spiritless. Additionally, I like to listen to music at low volume and I got used to the situation that the dynamics is lower than while listening to loud music, but with Atom Amp+ I feel the dynamics in the midrange disappear way faster than I would expect. That’s not a big deal in that price range, especially when you’re listening to the music louder.



The treble is again very correct. Not too bright and sometimes hides some details, but yet again, I ate a more expensive dinner last weekend than the reviewed JDS Atom Amp+ Hevi costs. Yes, you can blame me, but let’s be fair if the amp would cost $1000, or even $500, then I would probably complain a lot about it, but since it costs $114, then I have to be gentle because it’s a very decent headphone amplifier with great driving capacities.
So treble can be too smooth in a negative way, and dull, but overall if you’re looking for a neutral sound that won’t push forward the mix and master errors at an entry-level price tag, then reviewed JDS Labs Atom Amp+ Hevi is very good. A good example can be Californication from Red Hot Chili Peppers I love the song, but I hate the sound engineering – the dynamics suck, sometimes you can even hear unexpected distortion, and while listening with “better” amplifiers I’m just fast-forwarding to the next song, but here I just feel it’s fine.

The soundstage is decent and I could finish this paragraph here. I mean it exists and does the job, but don’t expect anything extraordinary. The dimensions and the layering are both alright. Due to good channel separation, it scores a lot in terms of the width of the soundstage, but the depth is rather flat, even when I paired the Atom Amp with SMSL SU-9 which improves it. While listening to music I feel like it’s a wall of the sound that separates the back of my head from my face a little bit.
That would have been a true issue, but yet again I need to write these three digits “114” – the price in US Dollars. As a reviewer, I’m spoiled by amazing audio gear. My interconnects are more expensive than this amplifier and I feel I need to keep the expectations on a bit lower level. When keeping in mind that it’s so cheap, yet again I have to admit it’s a great piece of gear. Again, considering the price, the JDS Labs Atom Amp+ Hevi scores great in this review.
What’s also worth mentioning is that this little amp get’s along with pretty much everything I tried it with. Doesn’t matter if you’re planning to go with IEMs, dynamic od planar headphones, it does the job with everything. This makes it a highly universal and useful device to have for such a small price. Doesn’t matter if you’re planning to use it as your main amplifier, or just in your secondary setup, the Amp+ Hevi will surely deliver a good quality signal for you to simply have fun with. Also, having in mind how small it is, it’ll suit every desk, even in the office, and shouldn’t grab too much attention.

Comparison​

JDS Labs Atom Amp+​

Now I just should paste a meme with Pam from The Office, because as I’ve already mentioned JDS Atom Amp+ and Atom Amp+ Hevi have exactly the same circuit boards and the only difference is in the case.
Many users were complaining about the weight of the OG Atom Amp+ and I know, now you probably see Paweł blaming that he can’t move his Feliks Audio Envy without a forklift, but actually that was a completely opposite problem. The devices from the Atom lineup are so light that some stiffer interconnects could cause it won’t stand correctly, but JDS labs had listened to requests and they replaced the plastic top case with a metal one, thanks to this you finally don’t have to worry that it will fly out the open window like a helium balloon.
Thanks to the used materials it also feels way better quality, the plastic of the older one is ok, but when you stack a couple of devices one on top of the other it scratches a bit, with the metal that issue doesn’t exist. Finally metal is a better conductor than plastic, so the temperatures inside the case are lower and the lower temperatures mean longer life of transistors and capacitors. The OG Atom Amp+ is known for great reliability, even long after the warranty period, so you can expect the Hevi will be like the old Mercedes w124 or Toyota Landcruiser.

JDS Labs Atom Amp+ Hevi Review — summary​

If you’re looking for an entry-level amplifier that can drive most of the headphones currently available in the market, then JDS Atom Amp+ is a no-brainer and I think it’s worth spending an additional $15 on better build quality and more metal used in the case manufacturing.
Another case where Atom Amp+ Hevi fits great is the office desk stack, the device has a small footprint, and as mentioned it can handle most headphones, additionally, it does not have the most engaging sound which isn’t the most desired feature of the audiophile gear, but in that use case, where music should be only a background, it would be an advantage for me.

And finally, is it worth replacing the previous JDS Atom Amp+ with the JDS Atom Amp+ Hevi? If you’re expecting any difference in the sound, then no, but if you have always wanted to engrave something on the top of your amp then yes (custom engraving is available on jdslabs.com).

Recommended!

Big thanks to JDS Labs for providing the Atom Amp+ Hevi for this review. I wasn’t paid or asked to say anything good or bad about this product, all of the above is just my personal, unbiased opinion.