HD-AVP includes the same high performance USB DAC implementation as DAC-10, but DAC-10 consist of a better preamp design using switch resistor technique. DAC-10 also includes other digital inputs that go through the same DAC.
In the HD-AVP, only the USB input goes through the stereo DAC for pure 2-channel audio and the other digital inputs are decoded by the multi-channel DAC within the AV processor circuit. In summary, the HD-AVP has a USB DAC that is close to the DAC-10 performance, but offer many additional media server and AV processing features.
Overall, HD-AVP offers tremendous value by combining high quality AVP and 2-channel stereo in a single chassis.