How to fix my detailed, accurate but BRIGHT system

I agree with the above recommendations. You don't have to buy audiophile room treatments, but you need to address some of the reflecting surfaces in your room. Glass, tile, and good sound wont happen, until you add some absorption in your room. When you say glass, I'm assuming you're referring to windows and not mirrors.

I wouldn't waste your money buying different equipment either, until you fix your room problems. All you need is an area rug in front of the speakers, and some thick drapes over the glass, and you can close the drapes for listening and then open them, when you're done.

What is the distance the speakers are from the front and side walls?

Rich

Throw a little Mcintosh into it

It's amazing what small adjustments to your speaker set-up can do to tame brightness. Play around with your toe-in, distance of separation, distance to listening postion, etc. I've also found that titling speakers back (or forward) ever so slightly can make a big difference as well.

It's interesting you don't mention you I/C's and S/C's. Why not start with them?

I owned Aerial 7B speakers, and drove them with a Bryston 4B SST, Bryston 14B SST, and VAC Phi 110/110. In all cases, I thought the speakers remained on the "bright" side and lacked sufficient bass to balance the top end.

While you say you like the Butler/Aerial combination, the Aerials have a pretty wild impedance curve. John Atkinson write in his measurements section of the Stereophile review:

Its plot of impedance magnitude and phase against frequency (fig.1) revealed the 7B to be a moderately demanding load, with a nominal value in the midrange and bass closer to 4 ohms than the specified 6 ohms.

These speakers are best driven by an amp that doubles power output as impedance is halved...so that the volume in the bass is equal to the volume in the mids and highs. Your Butler 2250 does not double power as impedance is halved.

Specifications:
• Rated Power (all channels driven):
2 x 250 Watts RMS per channel @ 8 ohms
2 x 400 Watts RMS per channel @ 4 ohms
1 x 800 Watts RMS Bridged (Mono) @ 8 ohms

The result is that the amp produces somewhat louder volume in the highs than it does in the bass, which causes a tonal imbalance that emphasizes the highs.

IMO, your amp/speaker match is not optimal.

The tile and glass in your room exacerbates the problem, so as others have mentioned, some room treatment will be beneficial.