Room treatment...what is the goal?

Good advice, Stanwal! You're exactly right.
I've had the same experience with various changes to my system, but especially with room treatment. What previously seemed like "sparkle" or "detail" turned out to be "hash."
Nemesis -- listen for a while, then, if you can, reverse the changes (go back to your original configuration) and you'll probably find out you prefer the well-planned and treated room improvements.

Agree with Stanwal and Ncarv.

I installed six 2'x4' acoustic panels on my sheetrock side walls to eliminate slap echo and ringing of higher frequencies. They certainly cured those problems, but the difference in sound made me worry I had overdamped. The panels were removable (but only slightly movable), so I experimented by taking down one panel at a time. There was a marginal improvement with only 4 panels, but for the present I am using all 6.

I also compensated for the lower sound (noise?) level by turning up the volume of the system. I found I could play at volume levels that would have been painful without those sound panels, and the sound is more satisfying simply because it is fuller. The sound is also better balanced because the high frequency noise no longer masks the bass and mid-range. I also understand that pre-amps sound better running at higher volume because of less resistance in the signal path.

I listen almost exclusively to classical music and attend many orchestral and chamber concerts. Since installing the sound panels, I have tried to compare the liveliness of various venues with my listening room. Disney Hall in LA is supposed to be a "live" hall (tending toward the bright side). However, I never detect anything like a persistent brightness. All I hear is more detail and no dullness in the sound. I think overdamped, dull sound results from eliminating overtones, not reverberation.

The objective is to eliminate echos, reverberations, vibrations, resonances. I think most agree, those phenomena, will interfere with enjoying your music. However the goal must be to achieve the sound you like that you prefer only. If it sounds dead to you I accept that it sounds dead. If you want more sparkle then ask your acoustical designer to advise you about removing some part of the sound dampening, but proceed slowly or you might rebound to the upper end tilt you didn't like in the first place. If your designer is arrogant and tells you to like it because he or she knows what is correct, then ask another expert, or experiment on your own.In any event don't suffer because of another persons taste or measurments.

If your designer is arrogant and tells you to like it because he or she knows what is correct, then ask another expert, or experiment on your own.In any event don't suffer because of another persons taste or measurments.

Great advice,especially the last sentence.

My experience has been similar to Dougmc's,I can now listen at 85db comfortably and the dynamic are much better. I also agree with Ncarv and Stanwal"s advice which is what I did and after staying with the changed sound I started to appreciate the more balanced fuller bodied presentation.