Pass X150.5 vs. X250.5

Interesting theory about the room. You could be on the mark there as there are absorber panels between the speakers on the front wall,and a panel at each first reflection, but nothing behind the listening chair and nothing on the ceiling, although one can go to far there too. Thought the live end-dead end theory was at work, but I'll try some absorption in the back too. Also understand where you are going with the class A amps. I was thinking in terms of total power, not class A power when I thought about the 250.5. I'd probably need at least an XA 100.5 to make it work in class A, but that is WAY above budget.

I would not rule out XA60.5s being able to drive the 3As to VERY loud levels - but, still expensive.

I agree that you should look at the room. IME, some adverse room effects, particularly in the high frequencies, are inaudible at lower volumes, but quite noticeable at louder volumes or during peaks.

Here is a 10 second test: Standing in a couple different places in the room, clap your hands loudly. What does the decay sound like? Is there ringing? You may have a flutter echo that is bothersome only on peaks.

If you do have a room problem, then adding diffusion at this point may be a better idea than adding more absorption, but both should have a significant impact.

Bryon

Bryon is right IME. Try diffusion on the back wall versus absorption.

Ceiling though is a nice area to address as it too is a first reflection point. But ceilings are a bit more difficult from an aesthetix stand point.

Ccanino,
Adding to the room treatment remarks made by Bryan and Ckoffend, I might suggest you temporarilly take your side wall 1st reflection absorbers and move them to your back wall (behind the listening position); reflections from the back and front wall are more troublesome than side walls and ceiling due to the lower angles of incidence which reduces apparent source width and spaciousness.

Diffusion - either 1D or 2D - on your back wall works well depending on your sitting distance. Note that the diffusion coefficient depends on the angle of incidence of sound, with the greatest diffusion occurring at 0 degrees incidence, and because of the lower angles of incidence from your speakers to the back wall, diffusion can be very effective in helping to add "listener envelopment," a positive thing.

Many people mistakenly walk in a room, clap their hands and hear slap echoes not realizing it does not accurately represent what they hear from the loudspeakers when sitting down in their chairs. Slap/flutter echos will be most audible with short transient sounds - and probably inaudible with sustained music. Be sure to have someone stand next to or over your speaker and clap their hands while you listen from your listening chair to detect whether flutter echos can be heard there or not.

Good luck and keep us posted.