I dumped solid state power for a pair of Carver VTA 180s to drive my Eidolons and have yet to come close to running out of steam. The Eidolon's go down to the mid 3ohm region. The Carvers have a 2ohm tap, I've been using the 4.
Tom, talk to Avalon or one of their long time dealers directly regarding room size and the proper model. I've heard Eidolon's in a rather small room and they did a great job. There is a reason the Eidolon's are expensive, lots of expensive components.
Go on line and look in the manual for speaker positioning. This is where most users get bogged down. Their position within the room is critical.
The timing and cohesive single source presentation of Eidolon's was a stunning revelation to me. I'd been blindly monkeying around with electronics, cables, and tweaks, for years. The day I brought my pair of used Eidolon's into the house I literally got off the merry go round.
It could be my age but we've yet to grow tired of the look of the Eidolon's. I'm fortunate to have a wife who is a music lover and understands the potential of hi fidelity.