I have the older 2009(?) version of the TADAC, paired with an Empirical Audio Turbo 3 USB Converter and the DAC has a pair of mullard 12au7's in it along with a Python Helix power cord.
That said, it beat out the MHDT Havana I also owned simply due to the built in preamp (crucial). Otherwise the Havana appeared close in comparison. Would be nice if the Havana had a built in preamp as well.
The TADAC also bested a Red Wine Audio Isabellina I owned for a time (and I'd like to thank Vinnie at Red Wine for his incredible customer service...one of the best I'd dealt with). The Isabellina was really nice, but a different animal with it's solid state design and battery power supply.
Opinions and tastes always vary, but the TADAC is the best I've owned so far, and not near the most expensive. Key thing though is feed it a low jitter clean digital input and throw away the cheapo chinese tubes. Tube rolling has a big impact on the sound of this particular unit.
Not sure why he went away from the 2009 design instead of trying to better it. The new version looks cheap/stripped down in comparison.