Hi Ear. The brightness/too prominent treble thing on some music has plagued my enjoyment of the 640's to a certain degree as some readers may remember from the past. Upgrading my cables to the Chords helped a little (more noticeable in the bass) but the 9.1's continued to give me a bit of a wince now and again on vocals.
I don't think there was anything wrong with them..they were more than capable of "rocking the kazbah"....I can only say what I was hearing.
I passed mine on in the end but only to try some old Celestions which were rubbish to me. (I think there was something wrong with these)
The top end seems to be the hardest thing to please from what I have read here on WHF . the subject comes up quite frequently and sometimes involves much higher end kit than mine.
I now have Dali Lektor 2's which have sweetened up the treble considerably (plus much more). They are still running in as I haven't had much time to play them.
I am still hearing tinges of sharpness on some vocals but a major step forward for me. I may be over sensitive to the problem because it has wound me up, but I am hopeful that the Dali's will eliminate the last bit of sharpness when they are fully run in.
ear:Nooby what was wrong with them? thought the 9.1 would tame the brightness of the 640a kit