So Ive been using my K DAC almost exclusively rather than my Matrix Element M for almost 2 months.
DACs are hard to review/give impressions on; especially in my case where Ive had limited exposure to a lot of DACs.
Im mostly coming from being used to the sound of the Sabre found in the Matrix since it was my daily for over 2 years straight.
Right off the bat, the only disappointing thing about the DAC is the build. While not terrible, my Matrix feels much more robust and Hi-Fi quality. The K DAC is too light and moves around easily plugging cables. The chassis on the Broadway feels nicer so I presumed the matching DAC would be of the same build and heft.
Besides the the Matrix, the iFi Diablo (Burr Brown) has been my 2nd DAC I've used the longest. Now, normally when Im unimpressed I question why I would use one device over a better component for example; I only use the Diablo when I don't want to sit at my desk like on weekend mornings when Id rather listen to music in bed. The Matrix is a more resolving and overall "better" DAC to my ears and through my set up with my Broadway vs the integrated DAC/amp of the Diablo; so I normally gravitate toward the desktop set up when I really want to hear my headphones (Arya SE, Diana Phi and my new Final D8k Pro) to a higher potential.
So that's where the XI K DAC has me. I could sell my Matrix and not really miss it besides the nostalgia of it being my first higher end intro to DACs. It sounds as detailed as the ASR approved Matrix but with a warmer or fuller sound. Its really hard to describe since DACs in theory shouldn't have a sound yet anyone who's tried various ones could probably tell you they hear a difference between the degrees of detail or holographic presentation they can provide to your music.
Theres something very "organic" sounding about the K DAC. Now, its not a true NOS since Soekris doesn't apparently venture there unlike some of the more sought after R2Rs like Holo so the various filters can contribute to different sounds. I normally stick to the linear filter which to my ears has a brighter, cleaner sound and closer to what my brain is accustomed to with the Matrix. The opposite filter closest to NOS is the soft filter. The soft filter has notable decrease in upper treble and upper mids and lows vs the linear filter but still provides enough detail to where something like the ESS chip Matrix isn't going to be missed IME.
Now, its also difficult to judge exactly how much of the sound of the K DAC could be further improved since Im frankly using the very affordable but convenient WiiM Mini Streamer with an iFi power supply and previously was connected directly to my MacBook via USB. Cant say the Streamer helped immensely but its nice not being tethered down. The streamer in the Matrix is optimized and is perhaps providing a cleaner, more direct signal rather than the freebie toslink I have connected between the WiiM and the K DAC.
But the K DAC still holds it own even with perhaps a more limited signal via the WiiM so it only has me curious about what a better streamer would provide for it.
I feel like I've typed a lot without really saying much so my TLDR; the K DAC is a detailed, smooth and "musical" R2R offering by XI Audio. Im sure we've all read that in countless reviews but my real point is that it sounds better to me versus the perfect measurements of the Matrix which is still a great DAC. Besides the build quality (mostly just how light weight it is) I cant really find a reason to prefer my Matrix DAC over it despite what the measurement crowd would say. Im sure the fact that its the matching DAC to the Broadway (which I really like) helps in finding that "synergy" rather than mixing and matching via trial and error. My Arya Stealth, Diana Phi and Final D8KP sound pretty amazing and I couldn't be more content with what I hear coming from this set up when I already know that theres even better systems out there.
I think the price could be lower or if the chassis were more robust then I can see this DAC as a great option for those who want to try a good R2R without going over the $2k mark. Perhaps like the Broadway though it will be over looked by non Abyss Diana owners when IME its a great choice for many planars which so far for me have been quite a few like Arya SE, DCA Aeon 2 Noire, Audeze LCD-2CB and XC, Sundara, Final D8KP and I think I even tried the Campfire Cascades (not a planar).
I would recommend checking it out. I think the Matrix will go for sale soon and this will be my daily for at least a couple of years.