Help me to tame brightness

I have always had problems with brightness in my system also. My listening room sounds similar to yours, basement 22' x 14' x 7' cement with two stacked wool rugs. I have Sony XA777es, EAD sig. processor, Ayre amps, cardas reference cables and Northcreek Rhythm Signature speakers with Kevlar drivers.
A friend but the same speakers with carbon fiber drivers and his sound much smoother. I just broke down and bought a set of the carbon drivers and you know my system isn't bright any more! I know this doesn't help you but I spent years and a lot of money to "smooth" out my system (bought equipment that is know to sound smooth) with our much luck and low and behold it was the speaker cone material all along.

Mapleshade.com has some remarkable tweeks that can tame
brightness in many cases. I have found that the more definitive the system becomes the more willing a person has to be in working with the source material. Fortunately, there are some great tweeks that can really help without major surgery to the system.

I doubt its the speakers fault for sounding bright. Put more of the blame on the room itself. All first reflection points should have some sound absorption material on it. If you have alot of bare drywall, the first reflection points are going to smear the soundstage really bad and make the speaker sound unnaturally bright. Your speakers and the room itself are the 2 biggest contributors/detractors of sound quality.

Since you didn’t change your room, I would say the speakers are the culprit. I agree more time may be needed. 100 or more hours is probably more like it.

Without calling for equipment change, here are a few suggestions. No particular order.

1) Isolation for both the CDP and Processor.
2) Couple the speakers with spikes.
3) Try a different PC on the CDP/DVD.
4) Try placing either a ring or 2 vertical bars of felt around/beside the tweeter. Staying about 1/2" from the driver itself and being about 1/2" wide. You can buy an easily removable two-way tape and attractive black felt from Michael's.

Isolation can help. Coupling can improve cohesiveness of the bass/midbass which effects the overall sound. I didn’t have good luck with that PC on my CDP. I really wanted to like it, but I kept going back to a Transparent Powerlink plus until I got a Virtual Dynamics P3, this ones a keeper. The Signalcable PC was to bright. The felt ring/bars can help reduced reflected energy and help absorb some of the laterally dispersed energy. You can also use 1/2"x1/2" or so adhesive backed foam. A soft one. Like you might use to seal around a window AC unit. I would still cover the adhesive with a two-way tape designed for easy removal or you might end up with crappy adhesive bonded to your new speakers.