Piano and Trumpet can sound bright


SYSTEM:
SPEAKERS...Celestion SL700SE
AMPS...Quicksilver tube 90 watt silver monos
PREAMP...Quicksilver tube LS non-remote...new model
Theta Miles CD Player
CABLES... Kimber 8tc/8tc bi-wire (speakers), Kimber kcag and silverstreak (interconnect).

Any thoughts?... to loud, artist style (Red Garland, Miles Davis), aluminum tweeters, cables, room acoustics
zoot45
Some of that zip may be diffraction from tweeter off the front baffle. You might try a large ring of 1/4" felt around the dome. This will slightly pad down the tweeter while improving coherance.
If you're up for a speaker change, you could certainly change that quality in the sound. However, you'll change pretty much everything else too. I'd try replacing the silver streaks with something that's all copper - there are tons of options.
I hear live trumpets often at the local jazz venues. Yes at times they can be bright but never are they irritating or harsh.they don`t lose their inate beauty of tone.