Help me to tame brightness

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.

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.

What are the walls made of, poured concrete, or sheetrock, or paneling? What is the ceiling material. My intial response would be to deal with the room since that is typically the biggest source of problems.

Companies do not design equipment to be bright, or incorporate other flaws. It sounded good enough in their listening room for them to want to sell it. Most system flaws are actually room flaws. I suggest going to http://www.rivesaudio.com and putting your room dimensions in their model. See what it comes up with, there may be a simple solution. This solution would benefit every upgrade to come.

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.

Stehno, I do use API Power Wedge 114 power conditioner. Appreciate your comments. Regards.

Take a look at dakiom.com for the $57 introductory stereo system special of two "feedback stabilizers" which may immediately reduce brightness. Also, I have found that running the "de-magnetizing" CD called the Densen D'Mag with its 3 minute cycle on repeat for a total of one hour has "broken in" a bright sounding system thus reducing glare and brightness. Similar results with the PAD and Sheffield CD's for burn-in and demagnetizing of every part of signal path which are still available either new or used on Audiogon. This has sometimes helped to avoid expensive, and time consuming replacing of different parts of various systems which initially seemed bright or affected by glare. These items can be used to optimize already good sounding systems, so you won't be wasting money even if you have to make later system changes to get the exact sound you need. In the good old days, there would have been the recommendation to use the Quad preamplifier with its treble shelving control to uniformly and minimally reduce the entire high frequency spectrum, as a quick fix with very acceptable, unobtrusive taming of glare and brightness. Unfortunately, that type of control never caught on. Any equalization is just not mentioned anymore, even when it sometimes has the potential to tame brightness in one second, giving the afflicted audiophile time to troubleshoot until a more elegant solution is discovered.

Keep in mind also that it's entirely possible your new speakers are just a bit more revealing than the old speakers. But assuming your new speakers are not the main problem, I'd have to guess it's perhaps a little bit of everything.

However, with a bit of reseach, you might be able warm it up with a certain richness.

For example, a Rotel amplifier is a solid state known to be somewhat dark and rich in sonic character. This could be exactly what you need to balance things out a bit.

Based on your words, it also sounds as though that you have not implemented any type of AC line conditioning. If your equipment is on the bright side of life to begin with, then unconditioned AC will only add distortion and harshness to an already bright sound.

-IMO

I think any speaker should be broken in for 300 or so hours before you consider it's sonic merits

I'd assume it has to be the speakers, and what I would do is continue to allow them to break-in. I think you may have broken in the tweeters, but not yet the mid and LF drivers. Give 'em a couple of hundred hours before starting to worry.