Review of TDSS Upgraded NuPrime DAC-10 & ST-10 by John B.

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I just got my modded stack back from TDSS. Before I start, let me say I've used several dozen good SS or Class-D amps (no tubes), so these reflections are on that basis. My audio friends have several very good tube amps, but comparisons with them would not be valid.

From the first notes I knew the mods were a great success.

I loved my stock DAC-10H & ST-10 units for all they did so very well, but felt they could use a tad more air and openness on top compared to my favorite amps. Well, that one caveat, not a showstopper before, is now gone, gone, gone.  From Bach fugues to Alison Krause to Ahmad Jamal and Dimeola/Dilucia/Mclaughlin Live to Andy Summers' power fusion, the modded units put me in the venue in as convincing fashion as I have ever experienced from 2-channel. The overall sonic signature and balanced tonality is much the same as the stock units, but the soundstage, noise floor, very low-level detail and airiness is greatly enhanced. Separation, width, depth and most notably... the sense of performance space... is the best I've ever had in any system of mine. Images often float in the air far away from the speakers on well recorded material. It is very cool to experience this 3-D presentation.

This is the best amplification I've owned, and up there with the best non-tube gear I've heard anywhere. A friend has a big $$$ Spectral stack, and this reminds me of that for its speed, transparency and low coloration.

Note that these upgraded versions are very, very clean and focused; they add nothing I can tell, neither warmth nor brightness nor any euphonic editing. As in all matters, this may or may not match your tastes and system.

Kudos to NuPrime and Bob Smith of TDSS.

Bob tells me they take a while to fully break in, and I can hardly wait. They are worth every penny and then some as is, if SOTA transparency is the goal. If you already like the sound of your NuPrime and you've been thinking about the TDSS mods, for my money this is the real deal. It really shows off what these awesome pieces can do at their best.

If you don't own NuPrime, I think you'd have to pay far North of $10k for a HP amp, DAC, remote preamp and power amp to match these upgraded units, and much more to better them. On top of that, they are very small, energy efficient, well built and look cool. Am I in love? You bet!

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I've put about 80 hours on the stack now, so here's an update.

The big story with the mods continues to be the enormous expansion of the soundstage in 3 dimensions compared to the stock units, which are already pretty good in this area. WAY outside and above the speakers, with the space of the venue clearly and accurately portrayed.

Easily the best I've ever had in a system here, and not far from the best I've heard in high 6-figure systems.

No downsides I've found; in fact I can't identify any sonic weaknesses at all. I think the soundstage has improved very gradually during break in. Not dramatically so, I suppose. I'm told 200 hours is the expected break in; if they get better, so much the better, but I already feel I've drawn an Aces-high full house. A very nearly state of the art remote controlled preamp, headphone amp, DAC and power amp in a small, integrated package for under $5k new, including mods? I wouldn't have thought it possible.


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I had my Dac10H and ST-10 modded by TDSS, and it was a very worthwhile improvement in depth, clarity and dimensionality of the presentation, and I'd happily do it again. Considering the reasonable prices of both the components and the upgrades, I see it as a package deal, with the result being a super bargain on excellent sounding, well designed gear. Since having it done a couple of years ago I've not even thought about changing them. They really are quite sonically invisible, showing everything in the system except themselves.
Good luck!

John B*****