Another day, another DAC: S.M.S.L. Sanskrit 6th mini-review and commentary

I decided to give the S.M.S.L. Sanskrit 6th a whirl recently to see how things stood on the cheap USB DAC front.
S.M.S.L. has long held my respect for trying hard to deliver high-quality audio at an extremely fair price. Just a quick look over the DAC's circuit board tells you that these are people who care about their work - from the etched S.M.S.L logo to the clean, logical parts layout. The build quality is apparent too in the simple, nicely finished case, which matches my Sapphire headphone amp (shown below) in "mini-me" style.

Part 1.

It's all "there", from the Cirrus Logic WM8740 DAC and NJM2114 opamp output with what looks like discrete transistor pair output buffers. The board generates 3.3 V, 5 V, and +/-12 V rails from the 9 V DC input. Other components include a 7805 voltage regulator, cmedia CS6631A USB audio processor, and Onsemi LC89091 receiver. A lot of stuff for the price. So it's a frustrating disappointment to have to report that it doesn't sound as good as I hoped. The sound is smooth, clean, and nicely detailed however. So, for the price, here again, one can't complain: it does what one might reasonably ask of it. It's hard to put one's finger on the source but musically, it fails to rise to the occasion. The sound is weak, feathery, light. Complex passages dissolve into incoherence. There is no power reserve. Perhaps due to the switching power supply whatever charge pump circuits are used to regenerate the internal voltage rails. Perhaps distortion from the transistor output stage, or insufficient filter capacitance near the op amp. These are just educated guesses on my part, but it does raise an interesting point: what does a DAC need to get truly high-end sound?

In Part 2. (coming soon), we'll take a look at exactly that.

 

[rjm]

Part II.

Unlike speakers or power amplifiers, a DAC isn't something you can just throw money at to make it sound good. The best-performing DAC chips are not especially expensive, and line level audio circuits are not especially complex. Although adding a good power supply requires a moderate budget, above a nominal threshold we should expect little correlation between build quality and sound quality. It's going to come down to the designer knowing their craft in both the digital and analog domains. Both in not making any mistakes that lead to noise, distortion, etc., and in choosing topologies that sound better over ones that sound worse.

So you pick your choice and you take your chances. Listening evaluation in your own system is going to be critical, and that poses problems in today's online marketplace since outside of the very high end that's just not going to be possible unless you buy a bunch and sell the ones you don't like - a far from ideal scenario. I suppose you read reviews, but the landscape is littered with paid endorsements, and even if they are legit - it's hard to know who's judgement to trust.

My problem is twofold: I don't have the wherewithal to make my own (which is how I solved the same issue I had with headphone amplifiers) and I don't have the money to just go out and buy something really high end which - despite what I wrote above - would most likely solve things.

Instead I've gone through a carousel of DACs which have variously promised to punch above their weight, only to remain disappointed. The best I've had so far is the Ayre Codex, which if it wasn't for the high distortion of the output stage would have been perfect. The rest, like the Sanskrit, have inevitably fallen short.

In terms of nominal alternatives, I shortlisted the Chord Qutest/2Qute, Project Pre Box S2, and the iFi Zen DAC Signature V2. As a dark horse alternative, there's the Denafrips Ares II. All but the Denafrips are built around a switching power supply and 5 V DC input. The Chord stands out for the custom-programmed FPGA DAC, the Denafrips for the R2R ladder topology and traditional linear power supply. The others appear to be permutations of off-the-shelf DAC circuits the same as the Sanskrit. While I can appreciate that programming your own DAC chip is a significant effort equivalent to building your own op amp from discrete transistors, I don't follow what the problem is with off-the-shelf DACs that drive Chord to go this route. I need to do more research on that. The Denafrips analog, old-school approach wins favor in my heart, but reviews are mixed at best. Even if the topology has merit, the difficulties in execution may make it impractical at its price point.

Anyone have a line on a nice sounding model for less than $1000 US? The only other requirement is that the chassis be half width or smaller...

 

[rjm]

A quick followup on the Sanskrit 6th DAC: I did try it with a decent linear 9 V power supply but it didn't materially help matters much. Gave it one last chance, routed through the Teac HA-501. The smooth, airy, detailed top end is commendable. There is a huge suckout of musical energy from the lower midrange on down, however. Something I have learned to associate with RFI or oscillation even, though I can't say for certain whether that's the case here. Anyway, I can't really recommend it.