I sure hope your amp is 1-2 ohm stable, Avalons are infamous for presenting extremely demanding loads...
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.
Vicdamone u sure you don't need to use any $50000 cables and tweaks to match the Eidolons?
Kidding aside I think placement and linear power (triode amps) are the two main things. At least 60 inches away from the front wall and ceiling reflection treatment are crucial. The accuton mid has a very lean character that makes it airy and open at the expense of warmth.
I have a similar room as the OP. struggled for years to deal with early reflections and bloaty bass. Maybe just cos too cheap to buy $$$ cables.
John I don't doubt your assessment regarding the mid driver. When I auditioned Eidolon's at stores and shows I constantly walked away from them because they seemed overly warm compared to the other speakers, not to mention I couldn't afford them.
What I was actually hearing were speakers that had standout bass or treble and I assumed they were better. It wasn't until I got the Avalon's home when I realized I couldn't hear the tweeter or the woofer because they are so cohesive. And in an instant I realized exactly what I had been fighting all those years.
I get a very similar feeling from some Vandersteen, Thiel, and Rockport, systems.
Do you have a pair of Eidolon's?
The first time I began to understand and hear what Avalon does was with a friends pair of Eclipse. I have recommended them to a few friends who still have them. Unfortunately, the Eclipse tweeters are no longer available.
I have a pair of monitors in our little studio powered by some Hypex nCores. An amazing combination for monitoring recording. Not exactly meant for casual listening.