Access replied and said that the hiss will be reduced if I use low-impedance headphones. I don't think they understand just how loud this hiss is. I explained that I have been using Philips 32 Ohm studio phones which are already low impedance. I also tried several other sets just for good measure. The results were the same... a hiss added to the signal that is MUCH louder than the background noise I've ever heard from any headphone amp. It's not a little normal background noise. It's a failure of some sort.
Hopefully they will respond to my additional input.
The headphone amp on the Indigo and surely the KB is just a simple fixed-gain amp. I would imagine the gain is between 3 and 6db. If they don't offer any solution I will just replace the electrolytic caps on that little board.
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