Amir's measurements (Audio Science Review) of the Oppo HA-1 showed that it has 2 different internal analog stages. The line stage, and the headphone amp. The first is cleaner (lower distortion & noise), while the second is more powerful. The headphone outputs are always driven by the headphone amp, as expected. One might think that if you're using the HA-1's line outs (whether balanced or unbalanced) then you're listening to the line level stage. But that is not how the HA-1 works. When it's in fixed gain (called theater bypass) mode, which bypasses the volume knob, the line level outputs are from the line stage as expected. But only in fixed gain mode. As soon as you enable the volume knob (turn off theater bypass), the line level outputs come from the headphone amp. Amir's measurements show that the HA-1 is still a great DAC, preamp, and headphone amp. And it delivered about 7 Watts (!?!?) to the balanced headphone output, which is about twice its rated output power. That said, if you want a DAC, headphone amp or preamp with excellent measurements, you can get ones just as good as the HA-1 for a lot less money - let Amir's site be your guide.