Using Adcom GFA-555s as monoblocks to power magnepan 3.3s in active biamp

Thanks again. There are some posts in various forums that it's worked, but just about as many opinion that it won't.  

I guess bridged mode isn't all that useful, given that most of the really power hungry speakers are 4 ohms.  I 'm sure there are exceptions. 

@jji666 jji666 Since the Magnepans are 4 ohm rated, however it’s only the bass panels I’d be powering, what are your thoughts on stability?

Bridged.., unstable. Not that desirable. Sharing an experience if it helps, and firstly:

Why? What are you trying to accomplish? More bass...? Quality bass?

Quality-stable amplification is more important than driving amps bridged into 2ohms or 1-ohm for that matter. Speaker PLACEMENT and the ROOM itself what I found challenged or benefited me most on the 3.6s I demoed for a few weeks. In my case, it turned out the speakers were just way too big for my room. Smaller Maggies did much better in my situation. A friend brought a pair over. Way better. We tried moving them all over the place, wider, more forward, straight forward, toed in/out, try everything. And, why does a single GFA-555 not do it for you, sounds like a room issue or some kind of a synergy mismatch. A 555 is no slouch in stereo mode, 331.9W into 4 ohms. If that’s not enough power, something else going on there, Best of luck.

I’m sure you will notice an improvement. I would try it, you have nothing to lose and you won’t damage the amplifier.

And, why does a single GFA-555 not do it for you, sounds like a room issue or some kind of a synergy mismatch. A 555 is no slouch in stereo mode, 331.9W into 4 ohms. If that’s not enough power, something else going on there

There's no problem to solve.  I had a single Classe CA-200 powering the bass panels and it sounded wonderful.  I moveed the Classe to power some newly acquired KEF R11s and temporarily put in a Nakamichi Pa-7 powering the bass panels, and it still sounds pretty good.

But since I had the open question of what is best in place of the Classe amp, and I have two GFA-555s, I thought why not try and see if they can well power the magenpan bass panels as monoblocks. Intuitively it seems two monoblocks of that power should do better than a single Nakamichi, but not if it's going to damage anything. 

The 555 will power Magies just fine but I would not bridge them.