Well Peter I will chim in on your claim that you feel it does sound a bit better when bi-amped by saying that my very first configuration when I bought the XPA-3 was running 12 guage wire from the L/R main posts of the Denon to the top posts on the M80's (removed the gold connectors of course...), then ran RCA cables from the L/R pre-outs to the Emotiva, and then ran 12 guage wire from the Emotiva to the bottom posts on the M80's.
I did nothing to the M80's as far as disconnecting the cross-over or any of that. All I was after was I wanted to push the twin woofers with all 300 watts the Emotiva supplied, and the top four speakers with the 125 watts the Denon supplied. It sounded fantastic, better than the Denon by itself I thought. I felt the bottom end was really, really tight. And as all of us M80 owners already know, they play tight to begin with. But a quick comparison left me impressed.
The only problem was, for whatever reason, once I pushed the volume up to around 85%, the right speaker would trip the fault circut on the Emotiva. I could not find a solution to this problem. I swapped wires, restripped both ends of the wire. Tightened things up, moved things around, pulled the power cord out of the wall, tried plugging it into other outlets... Nothing helped.
So I removed the wire running from the Denon to the top post on the M80's, replaced the gold connector, and just pushed them with the Emotiva. Problem solved. I'm still confused as to why this was a problem, but it didn't matter too much to me, because they sounded fantastic.
Still, I would have liked to have been able to do some comparisons between the two set-ups at 90 - 95% volume to really see if I could tell if one set-up was superior to the other. But I guess it wasn't meant to be. Oh well, I'm happy with it.
