[barkas]

I had the impression that something was not right with my for some time, today I tested it with a frequency generator, and behold, for example between 1100Hz and 1200Hz the balance wanders extremely between left and right (audigy2 platinum pro headphone out -> K340 (and I know it's not amped right this way, but for this test it suffices)).
Can this be some problem with the source or something I can easily fix or do I have to let AKG change the drivers (if that can still be done, I already asked akg per mail, waiting for answer right now).
Apart from that, it sounds good, strangely, a lot better than my super.fi 5 pro IEMs.

 

[mulveling]

I once got a K340 that sounded extremely unbalanced. I tested it and the right side showed an extreme dropoff around 4000Hz - it reached 10 to 12 db down relative to the left side, and stayed that way above 4kHz! 4kHz is the crossover point between the dynamic and electret drivers. I forget the exact measurements, but the rolloff may have started around 1kHz or 2kHz, like yours.

Clearly, the eletret driver wasn't working. I gave them to Larry at Headphile and he said he found a corroded internal part, I think in the crossover (looked like some liquid had been spilled at one point). He said he could fix them, but I sold them to Larry at that point and never heard how they sounded after the fix.

Apparently AKG has spare electret drivers, so if that's busted you can have it replaced.

 

[barkas]

I retested it with accurate data points.

balanced at 1100
at least 4db right at 1120Hz
balanced at 1160
strong left at 1180
leveling out to balanced at 2000
left again at 2800
balanced at 3100

gets better as the frequency gets higher, a light left is at 14000Hz again.

But it basically jumps all over the place.

Some of it can probably be attributed to my ears, but not all.