I've listened to a decent amount of NOS DACs (i.e. non-oversampling DACs) over the last few years. Now I am going to compare them for all interested. Lucky you! I will roughly list them in order of my least favorite to my most favorite. I will leave out one mystery DAC in particular, which was not only perhaps the worst DAC I've heard (and had an incredibly finicky USB connection, the only digital input), but the individual/company behind it was rather rude and pushy. You will just have to wonder what it might have been. Now, onward! Starting Point Systems TDA1543 DAC - Original model without the reclocker. If you've heard about the "magic" of the old Philips chips and non-oversampling designs, this is a good...starting point. Ha! Find one used, or bid on one to score it at a lower price. The TDA1543 chip is a budget chip and was designed as such back in the medieval times. You can expect very little to no zeros after the decimal point for distortion. You can expect somewhere around 12, 13, maybe 14-bits of actual resolution. The original Metrum DAC chips weren't a whole lot better on paper, to be honest. Still, it has a very interesting sound. It's not neutral, nor is it a technical marvel by any stretch of the imagination. It's actually rather euphonic or "musical," if you'd prefer to call it the latter. It has the usual, if not exaggerated, sort of sweet sound that non-oversampling provides. And the old Philips chips do have their own sort of sound, which you have to hear to understand. The bigger brother, TDA1541A, has a similar house sound, but with a lot more zeros and fancy looking numbers on the datasheet. The big brother sounds a lot better too. This TDA1543 DAC, or any 1543 DAC, really, is only worth considering if you want a cheap, entry-level, non-oversampling DAC to try and are curious about that old school Philips sound. One upside is this TDA1543 DAC does have rechargeable batteries, so it can be used on-the-go for 2-4 hours. That might come in handy for some! MHDT Atlantis - I had high hopes for this one, seeing as it uses the reputable AD1862 chip. However, I had some real issue getting it to sound right. The tubes made a huge difference. Some made it too bassy and wooly. Some made it too bright and thin. I'm sure eventually I could find a tube to make it sing, but it was a loaner with a limited number of tubes to try. I think with the right tubes, you could get good tone, decent, but not great staging, decent detail levels, and so on...but something is missing. I couldn't connect to the DAC. It didn't have that sense of magic for me. Metrum Quad/Octave/Hex - I'm bunching together the first generation of Metrum DACs because I think they all sound and perform similarly enough to not warrant me copying and pasting the same descriptions over and over. I'll be upfront and say there's no real reason to buy any of these today. The Musette is an overall better DAC than the Hex ever will be, so just get that instead if you must. The old Metrums have a very unique sound to them. They really excel with good tone (simultaneously neutral, sweet, and slightly earthy), stunning vocals, and fatigue-free listening. They are fairly fast sounding. The downside is they're kind of cloudy and mushy sounding, and they're way too smooth. Say goodbye to micro-details! You might not notice it at first, but once you do, you can't not notice it. Some will say the Hex or Octave Mk2 were big improvements, but I wasn't hearing it when I did A-B tests against the Quad and Hex. A few years ago, the overly-smooth, glossed-over-details sound was a common sacrifice one had to make if they wanted a good NOS DAC without buying some obscure DAC, a crazy expensive DAC, or some random TDA1543 or 1541 DAC from China. And the old Metrums did have something going for them. You could tell the designer had a vision he wanted to capture, and you could almost hear it. Almost. While this line was a necessary step to get to the next generation, those chips he used were letting him down. Audio-GD NOS1704 (Discontinued) - A rather syrupy, slightly bassy sounding DAC. Good resolution overall, but the stage is small in about every way you can imagine. I took it over the Hex because of the lower cost and the extra resolution. Supposedly the other Audio-GD DACs, especially newer ones with the upgraded DSP, are much better. I'm only listing this for completeness. Metrum Musette - The Transient modules in the new Metrum DACs have paid off nicely. You can read more about them on Metrum’s OEM site. The Musette uses 1 module per channel and doesn't have any FPGA magic to resolve a 24-bit signal. Thus, you are left with what is essentially a good performing, 16-bit, non-oversampling DAC. I think the overall sense of detail, tone, sharpness, speed, clarity, and so on have all been brought up a big notch since the first-gen Metrum days. Yes, I would take the Musette over the Hex. The Musette is a fairly well-rounded DAC. I think it would have been better to price it below $1000, so keep an eye out for used models or other discounts. My main criticisms is that it lacks the liquidity of the better, second-gen Metrum DACs, that it can sound a bit edgy at times, and that it has a fairly narrow and claustrophobic soundstage. Still, it's a good, mid-tier, non-oversampling DAC. It will give you a taste of what NOS is all about, but it will only give you a peephole into what the newer, bigger Metrum DACs are capable of. Note: Below this point is where I think NOS DACs start to really take off, so to speak. Holo Audio Spring - This one is tricky to evaluate, seeing as there are various "levels" of this DAC with various upgrades and tweaks. A tweaked model from an international source will likely differ from the Kitsune version, though some upgrades will be shared. The model I heard was an early KTE Level 3. Mine was essentially a Level 2 with the upgraded silver power transformer. That's it. What makes this hard is that I found even fuse tweaks made a difference in sound, for better or for worse, so what you've heard in a Spring could differ from my experiences based on these factors alone. I found the Spring to be full bodied, even very slightly bassy, with a wide stage, inky black background, and an overall smooth but occasionally hard sound. It sounded focused, driven, and forward. In-your-face, actually, like a brute force approach. Macro-dynamics and swing were great, though sometimes at the expense of micro-dynamics and subtleties. At face value, it seemed to be a detailed, resolving DAC. Little things seemed to pop out easily, and background noises came forward. It wasn't until I did some lengthy back-to-back tests against other DACs that I noticed a couple, minor things that bothered me. First, stage depth was somewhat compromised, not unlike the Jotunheim as an amp. Most of this comes down to the forward nature of the DAC. The second was that last bit of air, reverb, and decay. It was there, but it seemed like it was stifled or being held back a bit. Or, if it was there, it sounded forced. Still, I found the Spring to be a very enjoyable NOS DAC. It's one of the better ones for sure. I would inch people towards the Level 1 or 2 models rather than worry much about upgraded versions, for the sake of value. It's fun, engaging, and powerful sounding, but it's not the most nuanced DAC I've heard, nor does it handle delicacies as well as others. Metrum Menuet - Here is where the new Metrum “Transient DAC module” magic comes into play. Moar modules, FPGA to split at 24-bit signal in two (read up on how the Metrums split the data, process it, and piece it back together elsewhere), moar case, moar heavy, moar dollars! Seriously, though, I think the Menuet is a big step up from the Musette. Those extra DACs with the FPGA make a surprising difference. After much thought, deliberation, and DAC evaluations, I've decided the Spring and Menuet are a bit more on the same playing field, whereas before I equated the Spring more to the Pavane. I changed my mind. Still, the Spring and Menuet are more different than better or worse than each other. The Menuet brings together that mysterious and nice "something" from the first gen Metrum DACs, which the Musette misses, with a suped-up version of the technical gains from the Musette. It's a neutral and fairly graceful sounding DAC, more so than the Spring. It handles micro-dynamics better than the Spring but is not as powerful when called for. It's not a forward sounding DAC, nor is it weak. Staging seems rather appropriate (we have depth!), and those nuances the Spring either skips over or brute forces, the Menuet handles nicely. The downsides are the Menuet can bit a bit too soft sounding. It's not as strong or incisive sounding as the Pavane or the Spring. It really suffers with single ended output. I found the balanced output on the Menuet noticeably better than SE out. If you are limited to SE inputs and outputs, the Spring does better, and noticeably so. If you can do all balanced, you may still prefer the extra heft, grunt, sharpness, forward drive, and slight bassiness of the Spring, or you may prefer the more even, delicate, nuance, and smooth approach of the Menuet. Audial Model S (in particular, Mk2, SPDIF) - The Model S is created by some sort of TDA1541A wizard. He went as far as testing various batches of 1541 chips and narrowed it down to a production year from a particular factory. He's tested all the variations of the 1541 to find the best performing chips. Fun fact, you don't necessarily need the crown versions to get that level of performance! Some of the standard specified chips perform just as well...if you know what to look for. Anyway, the Model S is a custom, modern DAC design that uses an ancient, Philips, multibit DAC chip. And make no mistake, there's a reason the TDA1541A has that sort of legendary status, along with the PCM63, AD1862, and UltraAnalog chips/modules. Interestingly, the Model S reminds me the most of the current, multibit Schiit DACs out of all these on the list in terms of overall tone, timbre, and background. That's not to say it sounds just like a Schiit MB DAC, nor should it necessarily, given it's a NOS design with an ancient chip. Yes, the Model S is technically limited to 16-bits, and 96KHz if you go for the SPDIF version. But it's a good 16-bits, and the measured results are quite excellent. The Model S in general has a great design, uses nice parts, zero-feedback output stage, and, an option I'd recommend springing for, high quality output transformers. There's a lot of meticulous care that has gone into the Model S. But, enough about that. How does it sound? Truth be told, I would take it over the Menuet and Spring, 16-bits or not. A lot of folks will tell you the TDA1541A is all mids. And while the Model S does have a wonderful midrange, it's lively and powerful sounding. While the Spring was able to capture some details a bit better and more clearly than the Model S, the Model S really pulled ahead once you got past that initial sense of clarity. The Model S captures staging, air, and other nuances and delicacies the Spring forgot, nor was it quite as relaxed as the Menuet (plus, with optional OPTs, Model S is great from SE out). Yes, despite the Menuet and Spring sometimes making use of their more-than-16-bits capabilities, going back to the Model S felt like everything had lined up in a "right" way. There are other tradeoffs with the Model S too. The noise floor is higher and not quite as clean, somewhat akin to the slightly grey or hazy nature from the Gungnir Multibit, but not quite. The upper-mids and lower-treble can be a bit dry or forward on the Model S. The low-end can be slightly murky sounding or focused more in the mid-bass, and I do mean slightly. But as I did my back-to-back comparisons, the way the Model S captured the actual music, with all its little nuances, is what stuck out to me. It's a modern take on that old school, multibit sound, just with a non-oversampling design. You really have to hear a good Philips-based DAC to get a feel for what so many others love about these old chips. Metrum Pavane - The Pavane is expensive. Very expensive. But it's also where Metrum's vision becomes realized. It shares a lot in common with the Menuet, just more refined. Bigger sounding, faster, better resolution, musical, alive...you name it. After all, it's a beefier design, uses double the DACs, and uses OPTs for the SE stage, so SE output doesn't suck this time. Balanced is still best, but SE is not gimped. The Musette is sort of like a prologue of what's to come as you move up the Metrum price ladder. It showed Metrum was done fooling around with its lesser chips from the first generation of DACs and was stepping up its game. But the Musette lacked some of that pleasant, magical nature of the first generation DACs. The Menuet is something like a Venn diagram of the first and second gen products. It's got some of that magic back and sheds off most of the Musette's weaknesses, but it's lacking that last bit of oomph and clarity that wows you. The Pavane pieces it all together, and things just make sense after that. Of course, the Pavane was the first of the new-gen Metrum DACs to be released, so go figure it's a more fully realized DAC! What can I say? The Pavane nails the tone and timbre down, has a good balance of liquidity and sharpness, has great staging/imaging/placement, is neither too laid-back nor too forward, digs deep into the music, with all its intricacies and details, and still retains that ability to not cause fatigue. Now, of course, some will find it too soft compared to the Spring, whereas I think the Spring is a bit harder than it needs to be. And I imagine many will still hear oversampled DACs are more resolving, whereas I and some others found the Pavane was the first NOS DAC without this tradeoff. I do think there are a few very specific times when the Spring is competitive, or possibly better than the Pavane (power and blackness, maybe?), but it's held back too much by its staging issues and its lack of digging out musical nuances. So, yeah, think Menuet, just noticeably moar betterer. The Pavane is seriously good. One of the best DACs I’ve heard. Metrum Adagio - This is Metrum's new DAC + pre-amp unit, and, boy is it super pricey. But there's more to it than just being a Pavane with pre-amp functionality slapped in! See, their other DACs use "DAC ONE" modules. Those are all 16-bit modules. The FPGA for 24-bit processing, which splits signals between DACs, is a single and separate module, outside the DACs. The Adagio uses the new "DAC TWO" modules, which combine two 16-bit DACs and an FPGA in each module all under one roof. Compared to the Pavane, that means effectively double the DACs, and shorter paths due to the dual-DACs plus FPGA in each module. It also has a beefier power supply. The pre-amp functionality isn't tied to an analog output stage, nor is it done digitally. Instead, the volume control affects the input voltage to the DAC modules themselves, thus raising or lowering the output volume. Now, how much this affects the sound quality, for better or worse, I have yet to fully determine. It’s tough, because you have to level match your amp based on the DACs output, which is tricky. You can always set the Adagio at max, which gets you just a hair over a normal DACs output volume, or closer to 3 or 4 o’clock, which matches a usual 2V/4V output, and forget it. You'll still be benefiting from the other upgrades in the DAC. Compared to the Pavane, the Adagio is a little more powerful and full sounding in the low end. The overall sound is simultaneously a bit more focused, sharper, and yet more refined sounding. The background is just a little bit blacker. The bit of extra body and sharpness makes things pop a bit more and sound more like they’re really there (example being hearing a vocalist make a “buh” sound versus hearing and tangibly feeling it, latter being Adagio). Staging and imaging stays about the same, albeit it’s possible the Adagio is a bit more forward sounding. It’s possible it’s just the extra focus and fullness making it sound more forward, which is what I think, while others that heard it thought this might compromise on depth. Either way, it’s still not a forward sounding DAC like the Spring. The Adagio is really just like taking the Pavane and taking it up a slight notch. The difference is smaller than the gap between the Gungnir Multibit and Yggdrasil DACs. One thing that struck me about both the Pavane and Adagio was their ability to capture the magic of the TDA1541A (when done right) and other vintage chips, but with clear upgrades to the sound and more modern abilities. Note: You can also get the Pavane with upgraded DAC TWO modules from Metrum now. The base Pavane still occupies that sweet spot of performance and price, albeit still expensive, but if you want the best, consider the Adagio or upgraded Pavane.