Now, I'll be the first one to admit that this is one heck of a cheapo amp. But it still does something really odd:

It only works when I reverse polarity on the RCA inputs (made special adapters for that purpose). With reversed polarity, it works fine except for some ground-loop noise that I will debug with the help of Tonys FAQ. But with proper polarity the noise gets worse and there is absolutely no signal coming through.

Any one want to take a gues what's up?

Armin