Hello, I have encountered a serious problem with UD120 (or, more specifically, with its driver) - at least in Windows 8.1, it keeps resetting the windows idle idle timer. So while UD120 is plugged in, the computer never goes to sleep, turns of its display, starts defragmentation/trimming, indexing etc. etc.
This might be a workaround around USB selective suspend problems someone mentioned, but if intentional, it is a really terrible way to avoid them.
I was trying to find a reason why my display does not turn off after 10 minutes, so i installed http://www.daanav.com/free-idle-timer-utility-for-windows/ and voila - the timer is on 0 seconds all the time. Once I unplug UD120, everything is back to normal. Tried changing ports, connecting the DAC to USB hub and many other things, to no avail. Seems the weird driver is the culprit.
EDIT: OK, so the UD120 dongle is an USB Composite Device consisting of BRAVO-HD iAP Device, UD120HS (the soundcard/DAC itself) and USB Input Device containing HID-compliant consumer control. Disabling the Input Device in Device Manager made the idle timer go normal. Was the only purpose of the device to reset the timer? Also, disabled the BRAVO-HD iAP Device, everything still worked well. Noticed no cracks or anything after being idle, so I am totally happy now, I just do not understand why there are the two USB 'devices' (one useless and one idle-hampering) bundled with UD120HS.
https://www.dropbox.com/s/g3b3hqz3s1mzs3y/ud120.png?dl=0