I bought an AKG K702 a while ago when it’s on sale. While it sounds awesome when plugged into my old good M-Audio Fast Track Pro, the same cannot be said about the headphone jack on my PC at work, so I felt the need for a portable standalone USB audio DAC and headphone amp. And of course --- why not build one myself!
* USB in, 3.5mm TRS jack out
* Analog volume potentiometer
* DAC max data rate: 24 bit * 192 kHz
* Max output voltage: 3.9 Vpk = 7.8 Vpp = 2.76 Vrms
* Max output current: 125 mApk
* Analog low-pass filter: -0.1 dB @ 20 kHz, -40 dB @ 700 kHz
I've spent way too much $ on this project --- would be a shame if I leave it in a naked state, but I am really reluctant to make a custom enclosure and have someone machine it because it's more $$$. So in I opened Digikey catalog, picked a box that roughly fits the main board, loaded the 3D model in CAD, put some holes in the box, and voila:
Now I need a drill press... better a mill. Or I could use my old good flush cutter and tear that damn piece of plastic off.