Sorry Buckeye you are most likely off on this one, A+B is parallel, not series. However, we are saying the same thing about Denon can do 4 ohms, as long as you don't crank it too high. Denon clarified this point in the FAQ section. Well, I am done on this one. Would be nice if someone like Gene would say something about it, or else someone could email Denon.
Hey Buckeyefan1, how about this, to prove that A+B does not put the A&B speakers in series, simply select A+B without connecting the B speakers. If it is connected internally in series you will not get any sound because the circuit will not be complete. If you still get sound from the A speakers, then it must be in parallel. Right, Buckeyefan1?
I have several units from way back that have the A+B selection, and I know they are parallel. Unfortunately my 3805 does not offer that option so I cannot do this experiment, but still, I have no doubt I am right.