Ralph, besides Classic Audio, what would you recommend to use with your amps? Also, do you believe that short length Mogami RCA cables are just as good as XLR? I mean 2497 wire.If you keep the cables short you can do pretty well with single-ended connections. I can't comment about the single-ended Mogami- not tried it.
Regarding speakers, Audiokinesis, older Quads (newer ones need the ZEROs), Sound Lab (with our bigger amps), Coincident, Devore, Lowther, PHY (will need a speaker protection fuse as they only handle 20 watts), most horn systems and single-driver systems, AvantGarde, Merlin, Magnaplanars (use ZEROs, Eminent Technology (may need to use ZEROs) Vandersteen, Certain Avalons such as the Eidelon, JM Labs, Rogers LS35a, certain Sonus Fabors, Pipedreams, and many more.
The trick is similar to what you look for with an SET or any tube amp using no loop feedback, which is to say that the woofers should be the same impedance generally speaking as the midrange. Dual woofer systems that are 4 ohms in the bass and 8 ohms otherwise don't work so well. The difference between our amps and SETs is that we can work with speakers of much less efficiency, but personally I do prefer efficient speakers as I like to crank the hell out of the system once in a while and don't see the point of struggling to do that.