Many thanks for your replies
Hmm, I tried going through the switches a bit, but I couldn't really notice anything this time - also moving to the second speaker outputs sounded pretty identical to me (first time by the way) But yes, swapping the left and right channels does make a difference - it sounds more balanced and better having them reversed
I've got to admit that I might be a bit confused by myself now as well, but shouldn't that mean one of the channels is getting more power than the other one? Would I be able to measure the output with a multimeter just to be sure?
My current speaker placement isn't too optimal - that's why I'm scared if there used to be a slight problem with the other channel which just got normalized again, but I'm thinking it the wrong way now as I might already got used to it before
Regards, Jouni