I've had this thing for a few months now and I'm noticing some problems.
Configured as follows, but I have narrowed it down to the Zero by trying it from a cd player with a different cable at a friends house:
-software: MPD on FreeBSD 7, using built in usb audio drivers
-sound module: Turtle Beach Advantage Audio Micro usb
-cable: generic 6ft spdif optical
-amp: zero
-phones : akg k701s
Issue:
The problem is intermittent, varying from unnoticeable (where I am not sure there is any problem) to dramatic.
It occurs in both channels more or less equally.
It happens at all volume level more or less equally (both with the volume on the zero and the source volume with the sound card mixer).
The sound is difficult for me to describe accurately mostly due to my inexperience with audio evaluation in general, but i'll try my best:
distortion is observed usually in the higher ranges however the sounds it corresponds to might be any range (from bass drum to higher stuff like snare/cymbals, I have one track with a mid range pad that seems to really set it off).
When it is 'noticeable but not dramatic', the music sounds a little overbright to the point of some distortion above a certain range.
At its worst, it reminds me of clipping, but as if the clipping is only happening at certain frequencies. It also reminds me of a ring modulator. I also want to use the word crackle, but that would seem to indicate sound with a lot of pops and peaks, which isn't really the case here (unless the peaks are fast enough to not be differentiable)
At times there is also a sort of sound like you might get playing audio on a very busy computer, as if it is about to start dropping frames, however it never actually has instances where the sound drops out.
There is sometimes some mild popping and crackling at times, and once in a while i'll get some random artifact, such as just a moment ago, it dropped to static in one channel for only a half a second or so.
From skimming around the thread it seems like other people have had problems that have been solved by replacing the opamps. What should I do?
(PS admins, how about starting a subforum for the zero? it'd be much nicer then having the giant thread)