First: This DAC was made 13 years ago. 13 years ago, its MSRP was about 500$ USD. I just bought it used for about 250$ USD. 13 years ago, USB implementation was poor. USB input only does 16bit/44Khz or 16bit/48Khz. If you want USB bitperfect for high-res audio, look elsewhere. I personally never use USB. Toslink is also available, but I found it funny that I could notice a subtle change: Less treble (but more sibilance!) from toslink versus spdif (coax) when A/B switching. Toslink doesn’t seem to want to do 192khz either. It tries a lot, but fails (my SMSL Sanskrit 10th does it, for example – or is the Moon 100D just honest enough to disconnect the signal when you don’t get all the 192Khz instead of “faking” it? That would not surprise me). Anyway, I’m always using coax, and coax seamlessly does 192khz, so it’s perfect for me.
If you want to see an old review of “this brand new dac”, here’s one in PDF from “Ultra High Fidelity Magazine” in Canada.
Now for the review: Tests here were done with the Moon 100D (duh) connected to an Aune X7S amp, and my Nad HP50 or Sennheiser HD6XX headphones.
I have to say, this DAC did not “wow” me at first. Mainly because the magic of tubes got me only a few weeks ago (comparisons below). The Moon 100D is a different beast, impressive in its own ways. Info is hard to find on this DAC made in Québec, Canada, but the manual says it’s got a BurrBrown PCM1793 chipset. BurrBrown chipsets are known to be “smooth and musical”. Still, don’t expect a boring DAC. It kicks asses. Its got very decent bass, and very decent, albeit smoothened, treble. I saw someone selling one recently because “he only used his turntable”. Ironically, my first impressions about this DAC were “my mp3’s and FLACs now sound like vinyl”… So maybe this guy should keep the Moon 100D and save a bit of money, hah.
If you’re tired of DACs sounding “digital” and “mechanical”, this is for you. Even an electronic music song I have called “sound of machines” (Blank and Jones - Sound of Machines - RhythmusRaum Remix Edit), which is the definition of digital and mechanical on all my other DACs (Xduoo XD-05 Basic, SMSL Sanskrit 10th, Sabaj Da3), here, sounds like… the analog master of it (assuming there is even one). The Moon 100D adds an interesting amount of smooth depth to everything. And if I say that about this song, just imagine what it does to well-recorded jazz. 
It’s interesting how the Moon 100D is apparently voiced to be a smooth, listen-to-music-all-day DAC, but every time someone, or a guitar, or a violin (etc.), sings, it “jumps” at you, like well-implemented tube harmonics do. Is this DAC a bit mid-forward, or mid-oriented? Maybe it’s just the impression I get because it’s just so full of dynamics and details and depth. The mids are impressive. Voices can sound eerily realistic. “Tom Waits - I hope that I don’t fall in love with you” sounds great. “Grayson Erhard - Like a Stone” sounds better than ever. Guitars and pianos got depth. For a DAC actually discontinued 10 years ago, it also does quite well with modern, “full-on”, “wall of sound” electronic music kick drums and the lowest bass notes (which means actual bass guitar is definitely not a problem). It might not extend down to zero hz (lol) like recent DACs, and I would prefer more “punch” at ~100hz for the drum kicks. Still, the Moon 100D also got the most thick and powerful lows and low-mids I ever heard.
Do I sound like I’m there, in the studio? Pretty much. A great deal, to say the least, for 250$ USD. Dare I say, maybe the Moon 100D is not the “bottleneck” in my system either, now.
But there’s sibilance. Possibly atrocious and dizzying sibilance, depending on the amps, headphones and speakers.
Treble is great. Cymbals and snares just sound real. The Moon 100D got a very smooth treble, but you will hear all the details in the treble region. I have been lucky with my system, because it pairs excellently (with my Aune X7S and my HD6XX’s, or Nad HP50’s). The problem is the highest frequencies. My guess is, in fear of making the DAC sound “dull”, they over-compensated the oh-so-smooth treble by adding peaks in the higher, and highest, frequencies. Or maybe the internal 24/192khz upsampling was a mistake. Depending on your setup, these peaks can either make the cymbals, snares and xylophones shine beautifully… or horribly. It does not forgive. It will punish you for choosing a treble-oriented amp, headphones, or speakers. For example, did you ever notice the sibilance at 0:40 in Lindsay Stirling - I Saw Three Ships? With this DAC, it will jump at you. MP3 files, yes even 320kbps mp3’s, are known to destroy cymbals and high harmonics at these very high frequencies, and this DAC can show it.
Don’t get me wrong. This is the best DAC I own. But with the wrong equipment, this DAC just becomes a tinnitus simulator. Never pair this DAC with treble-oriented or V-shaped speakers, headphones, amps. This will be bad for your ears or your equipment (probably both). Sadly, “Little Dot Mk2 → Moon 100D” sounds like the perfect match, but adds way too much sibilance and destroys the mids (tube swapping is an option).
Good pairings and comparisons.
In my recent Little Dot Mk2 review I said buying a budget DAC and getting a Little Dot Mk2 with Voskhod 6J1P-EV tubes was the best way to get to “3D audio” for cheap. I still agree with that statement. Now, this is funny: I’m A/B-ing and “Xduoo XD05 → Little Dot Mk2” sounds like I’m with the guitars and drums but the voice is farther. “Moon 100D → Aune X7S” sounds like I’m with the singer, but the rest is farther. You also definitely get more accurate timbre and more depth with the Moon 100D. But this is really like, two different flavors of greatness. You want great soundstage and imaging? Get the Little Dot Mk2 as an addition to your DAC. You want great timbre and mids? Get the Moon 100D to pair with your amp.
Bonus: Easy, seamless bitperfect audio.
With my android phone + UAPP + Xduoo XD-05, I always had bitperfect audio. Simply because UAPP (USB Audio Player Pro) “took over” the DAC. But it also meant you had to close UAPP to play a youtube video, for example. For a dedicated audio player or a dedicated audio box it’s not a problem, but for a personal computer, when you want bitperfect music and friends notify you and send you videos? Not practical at all. Well, for your PC, the Moon 100D got a wonderful feature: A red light shows when the signal is locked to a certain Khz, and it ABANDONS the signal when it cannot lock to it (lock to 44.1khz/192khz or whatever in between). Which means that if I pause a youtube video, 4 seconds later, the 48Khz light is off. Which means the DAC is available. Any Khz available. The result? Seamless bitperfect Khz switching on PC. I never was able to use straight ALSA plus bitperfect on Linux because, for example, pausing a Youtube video would lock my budget DACs (smsl, xduoo) to 48Khz until I closed Firefox. Even the Discord notification sound would do that (yes, it meant Firefox would “take over” the DAC until I shut it down, because of an audio notification of a few milliseconds… 
). But with the Moon 100D, you get seamless bitperfect audio, even on Linux!
Ironically enough, the Moon 100D was made 13 years ago and they figured this out, but this feature is not implemented (yet) in any of the recent “budget” dacs I tried.
I’ll come back here with more info when I try to plug this into my Emotiva B1+'s. But for now, that’s all, folks!
I corrected the review accordingly.
I have not tried my speakers or my tube amp with any ESS DACs yet, but with a cheap ESS “blueprint” implementation I’d expect actual sibilance problems with my system.
