A / B Switching

I don't think so.. Macs are tough.. You need a second amp. If you want to really A/B it right.. The OLD Mac way.. Was A or B or A and B. I like both ways.. It just takes a second amp.. A/B amps switches, are not a great idea.. like you said.. Different impedance matching problems with just a switch.. If the speakers are the same, impedance, that problem is solved, with an A/B switch, BUT the CRAP switch and cables.. LOL Your still stuck with that..

You're better off with the preamp A/B and a second stereo amp.. SQ wise.

Regards

OK let me look.

That one uses a Main and Remote push button option on the front Same as ok.. Don’t just push the button, while blaring either, I don’t know what will happen.. OK.. Turn it DOWN then push the button.. Just to be safe.

Remote and Main do not have independent volume control, (usually)
Tone control on one effect ALL the amps..

Route one set of RCAs from each, The mains and the remotes to the two different amps.. That Adcom be careful. With some of them and I’m not sure on that one..

The GFA 565s the DC voltage goes high and blows voice coils on the bass drivers..It has to do with a 6db first order XO there is NO cap in the path (speaker side). They (Adcoms) have leaky Dcaps and causes the IC boards to short.. A MESS. BUT Adcom is a great amp for the money. I still have 6-8 around here..I like the 5800s, Power house..Good sounding..when you get it warm..

It is easy to check DC offset, just google it, and see if the 555 is prone to.. Save you some money..Some bass drivers are tough to come by..

Have fun..

Regards..