MarkF786
500+ Head-Fier
I'd urge caution with regards to the volume mismatch. even a 0.5 DB increase in volume is easily detctable, and will very much sway your opinion. I've noticed the Internal dac has lower volume then most stand alone dac's. It must not be putting out 2.0v RMS.
By manually adjusting the volume when switching between DACs, it adds a random variable to the volume. Getting them to exactly match in volume on any given comparison was unlikely, so which DAC was slightly louder changed each time.
No matter which DAC was louder or softer, the difference between the two in quality was quite audible.