So far I haven't detected any tendency for it to become warm laying flat on a table, where only the top and sides are able to act as heat sinks. One thing I really like about the D1 which is also true of HRT's HeadStreamer (a similar DAC/amp) is that it runs cool. I knew before I ordered the Audioengine D1 that it was small, but when I removed it from the box it looked even smaller - about the size of a deck of cards but 1/3 thicker. Although there were no configurations for me to make the D1 work with my Windows 7-64 computer, the PC volume should be set to maximum and then the D1's volume control knob set to the appropriate listening level. Since the short (24 inch) USB cable that came with the D1 carries only the unprocessed digital signal, and the output to the headphone uses the cable that comes attached (usually) to the headphone, there are no cable issues per se that could potentially degrade the sound.

When I first connected the Audioengine D1 to my computer I was pleasantly surprised that it interfaced perfectly with no configuration effort.

Audioengine d1 dac 24bits