Unfortunately, kiwi did not finish this project. So I have finished the software and designed my own SMC board.
Have a look here: https://www.tonymacx86.com/threads/mactester57s-imac-g5-17-a1058-model.130197/ The SMC kit in the first post includes software (Arduino sketch, libraries, Xcode...
sorry for the late reply. The supply cap is 1000uF / 6.3V.
The coupling caps on the PCM2704 board were bridged, because the amplifier board also has coupling caps.
BTW: I've added a Cube review video to post #1
You made a great progress so far!
To prevent your USB hub from smoking, have a look here: #54
Does the WTV020 module work, if wired outside the SMC board? Looks like you already added the missing GND wire. The SD card compatibility is a bit of a problem.
To rid off the Audio hum, have a look...
I think, you should start with an easy standard case or a G3 or G4 tower. They are relatively easy to mod.
here is the newest video, showing my iMac G4 "HemiMac" and the G5, running Sierra 10.12
Thanks for the mention. I'm glad, that my video inspired you:
I think, that this fat GPU will not fit inside the cube. Also keep in mind, that cooling is a critical point in a Cube.
I would recommend to start without a dedicated GPU and use the integrated GPU instead. They are good enough for...
I have now finished a new "2.0" version of the Pro Speakers USB conversion
It uses a PAM8403 Class D amplifier board. They are available for about nothing on eBay. The audio signal comes from a USB sound adapter. The sound quality is much better than with the old version.
Attached are some...