Inverting and or non inverting amp?

Usually this is only in preamps (especially tube preamps)

Cytocycle:
Good eye and good advice. I have a tube based preamp (Rogue 99) and just found out that I should have flipped speaker polarity at the speaker ends. (doh!!) Have to be totally honest though, it doesn't sound MUCH different than before. I just wanted to know what amps do invert?

Typically for preamps the number of amplification stages with each inverting the signal determines whether overall it is inverting. Three stages would be inverted. I had a preamp once that had a invert switch. When you pushed it, another tube was in the circuit uninverting the three stage preamp. While there are two and three stage amps, I cannot think of a circuit that would need to have the output inverted.

If you can't tell the difference in sound use a CD with vocals , to hear the difference. If you still can't your speakers aren't setup to image correctly. There are lots of threads on speaker setup to help you out. Also the bass will be kinda sucked out, though keep in mind it is a subtle difference.