doggelito - That is definitely the question this situation drives you to.. Hardware or the sketchy drivers/firmware that has been problematic the whole time now.. hmmm.. One would lean toward the drivers/firmware obviously, but I did thorough testing (short of opening the box up physically..)
A couple of tests I felt proved beyond any doubt in my case were the 'straight wire' test and putting the box on another machine altogether (my laptop..) The straight wire test was just to connect a little flash player, like a creative zen nano, into the K8 thru the Aux Ins with a basic 1/8" stereo to double 1/4" cable W/O ANY FW1394 CONNECTION AT ALL, totally standalone hardware. My left output still had no signal..
Connecting the K8 to my laptop with Sonar6, Winamp, Powerdvd, etc. had the same results as my desktop.
When I tried different drivers the problem persisted. I tried pretty much anything and everything you could think of. At first, a workaround was effective where I could crank the left channel with some hot signal and it would crackle and start to pass signal again. It even seemed related to sample rate change at one point where some apps would change the samp. rate and the left channel would go off. That made me think firmware too, and I had read about some problems with this with others. BUT... luckily (I guess) the left channel finally sh*t out completely and wouldn't output anymore at all.
The bottom line for me was the K8 was still under warranty, but I don't have a warm fuzzy feeling about this box's "tank-like" appearance anymore - which is not good for something you'd like to use with a laptop on location.
I think we are going to start hearing and reading on this forum and others about konnekt units that are being sent back for these types of hardware repairs. I am starting to see it.. if I get some more time I will look around and see if I can find some of the posts I've read and link them here..
If you can prove w/o any doubt that it is a hardware failure, maybe you can persuade TC service into replacing the unit w/o charge (assuming it is outside of warranty time.) I would start preparing your info to present to them, in my case, I was convinced a firmware update wasn't going to 'heal' the box somehow.
Anyway, gotta go. My K8 seems to working for now, better try to maximize it's "up" time.
Good luck!