To much high

Definitely treat the room. And, as has been suggested, going to a different IC can often help with the shrill highs. Although I prefer silver cables with our tube-based system, I found the Audience AU24 IC and the Analysis Plus Crystal Oval both took some of the high end edge out that is present with the silver IC's. There are many excellent options out there.
Hope this helps.

Guys, thanx for the advice, I will experiment with placement and some absorbing materials. And Didactically, being an ex-radio engineer, I know how original sounds, and I know these speakers are a bit bright. But because I fell in love with their potential I'll try to squeeze out every last drop that's in them.
Jeffreybehr, if I would use a resistor to reduce tweeter output (say, 1 ohm - 5 watts), wouldn't the best place be in the '+'-cable between cross-over and tweeter? I don't know, that just seemed the most logical place, but I might be wrong here, so any advice would be appreciated. And then: is it possible to get to high? :) But you're right, I probably meant 'too much high', but since I'm from Holland I tend to mess up things like that......

Satch:
Chiming in: the room (some expense). Placement (no expense).
What lead you to silver speaker cables? Depending on implementation some silver cables can vary the highs quality... Might you have any old speakers cable to swap for a test (no expense), a friend that could lend a hand here ( you will know your next expense, if they work you don't return them one less freind though!!)?

Hah! Friends only cost money, dropping by at random, emptying the fridge, so losing one is only a good thing :). Seriously, I chose the cable since it went well with my old speakers, and I do have some old pieces lying around, so that's one experiment that's on my list....