No idea. It's a second hand ex-commercial item, pretty well built, a HP, my wife's machine. It most likely is an all-in-one chip on the main board. But it's good enough to pick up the subtleties with different formats. Some time ago someone, I think Bruce, posted a number of versions of the same music actually mastered at different bit rates, and the same story was there: the denser the data, the better the sound was. So one would say in that case the poorer resolution files had "lost" information that was encoded in the higher.
Yet, here was a nominally quite poor information file, the MP3, going in the other direction, in terms of acquiring "quality", by resampling in a separate software exercise, and there is a similar result.
My take is, that especially with MP3 the processor has to do quite a bit of digesting to recreate the sound information, with a normal WAV only the DSP filtering in the DAC has to work hard, and finally, in the heavily upsampled, 24/192 version the chip basically can just run the musical data through with minimum fuss. So it's the level, the amount of computer style processing necessary to turn the file into the analogue what counts, that determines the end quality.
Frank
What's the model # of the HP?
Tim