advice on brightness

Its your Source. Sell it and apply the extra money to a better source.

...tryin' to think of something other than applying to your system Valhalla speaker wires and interconnects or something mega-uga.

Firstly, I'd try to unterminate your speaker wires and use a bare-wire connection to your speakers and to the amplifier if possible; bananas in general do not provide the tight contact and only expencive locking ones are OK to combine a contact quality with convenience of plugging them on and off. Clean wires off once per week or two with 99% alcohol or any you'd find professional cleaning fluid.

Spray the volume control of your amp with anti-oxide fluid or replace it with DIY stepped one(piece of cake actually) from www.marchand.com

Increase the angle of radiation of your speakers by placing something under: halfs of tennis or ping pong balls, hockey pucks.

Tweak your CD-player with the sam budget tweaks such as pieces of hockey pucks, halfs of tennis balls...

Power line conditioning and room acoustic treatments, anyone? Come on!

Speakers - according to the NRC's measurements, your speakers have a broad peak from about 750hz to 1500hz. This will overemphasize high vocal fundamentals, like sopranos, and instruments in the same range as a soprano voice and will more likely be perceived as brightness than a peak in the treble higher up. After dipping into the treble, there was also an on-axis rise from about 7khz up through 10khz and beyond from which you might perceive some sibilance or sizzle.

Walls, doors and windows reflect everything. So does the ceiling. Height of speaker stands. Toe-in. I wouldn't toe them in. Furniture. Leather and wood are reflective.

It isnt your amp. Your amp is a pretty good one to use with those speakers in fact. Nor can cables add any excess energy. Maybe there are cables that can function as tone controls in quieting the top end some, but there aren't any that can deal with the problem in the upper midrange (old school definition of midrange). I really doubt that your cd player is a problem either.

Drapes, soft furniture, room treatment. Or replace the speakers.

I agree with paulwp except for one issue, that is toe in. One of the ways of reducing side wall reflections is by EXTREME toe in. Try pointing the axis of the speakers inward well past the the listening position, say 45 degrees from straight ahead and see if that makes any difference in the peak, then bring them back towards the listening position til just before the peak become evident again. You may find that this will focus your center image and expand the listening position as well. Good luck.