The Audiobyte made a massive difference to the DAC2 for me. Previously I was using an Empirical Audio OR4 into SPDIF (although the OR4 offers I2S out it is a different format to the DAC2).
I'm not sure whether it is the Hydra-X itself, or rather the fact that the internal SPDIF -> I2S conversion is now avoided in the DAC2. I guess the latter, as I have faith that Steve at Empirical Audio knows what he is doing. I'd love to hear what the OR5 does - its I2S output is compatible with the DAC2.
Really, this transforms the DAC2 into a new machine at a very reasonable cost. I'd definitely recommend trying this before spending on the W4S upgrade.
My summary is: DAC2 from I2S, wonderful: from SPDIF, perfectly good: from USB, unlistenable.
