I understand it's an old recording engineer's trick to drape a piece of toilet paper over the tweeter to tame the high frequencies. I've tried this on a few shrill recordings, and it works pretty well. It does, though, tend to reduce not just the highs in the brightness region but also in the region above that, which adds "air" to the sound. You might give it a try. It's almost free and it's easily reversible.
If your speakers are bi-wirable, you could also insert a resistor between the bass and treble inputs.
-Bob
If your speakers are bi-wirable, you could also insert a resistor between the bass and treble inputs.
-Bob