I don't doubt that for a minute.....after living with the IDA-8, I can assure everyone there is no BS.
So if you had to pick a combination, would you pick the DAC-9 with the ST-10, or would you pick the DAC-10 with the STA-9?
If depends on the emphasis of amp or DAC. But in this case, it is not a fair combo.
ST-10 is clearly on a different class, right below Ref 20, than all other amps (ignoring power, because even though a good power supply affects the sound, but power alone is not a quality characteristic, it is a requirement).
The difference between two NuPrime DACs are not that far apart. Normally a $749 DAC-9 would not be considered reference class, but things have changed from the past few years. DAC chips are getting closer in performance. But more importantly, we also developed new circuit capability (such as FPGA based switch resistor network for volume control that bring traditional $3K to $5K preamp design to a $749 product) and design knowhow. A new US dealer just commented that DAC-10 has the only good sounding ESS implementation that he has ever heard. That might be a bit bias, but my point is that it takes much more to make a DAC sounded good, preamp being the most critical part.