Can I replace tweeters to reduce sibilance in monitors?

[jorge]

I have been using Dynaudio BM6P passive monitors for a couple of years. I really like them, except they produce too much sibilance on some vocals. This happens even with well mixed commercial recordings and I think the problem is with the monitoring system, specifically the tweeters, not the recording system. The monitors are driven by a Crown K1 power amp from a Mackie 1402VLZ mixer. The problem occurs whether the DA converter is a MOTU 2408 MkII, an M-Audio Delta 66, or a very good quality CD player. The same recordings don't have too much sibilance when I listen through Sennheiser HD600 headphones, or most other headphones, the S's and Z's are clear. My studio is 13x15x6.5 feet, and somewhat on the dead side with large rockwool bass traps in 2 corners.

What can I do to reduce the sibilance of the monitors?
Are there any other tweeters available that would match the BM6P tweeters reasonably closely but would not overemphasize the sibilance as much?

I was looking at the ScanSpeak D2905/9500, at this URL:

http://www.madisound.com/pdf/scanspeak/ ... 50000e.pdf

Their frequency response looks pretty flat and they do not hype the 5kHz to 10kHz range in which I have read that sibilance occupies, but I have no idea of the sensitivity or impedance response curve of the Dynaudio tweeters they would replace.

These ScanSpeaks look even better, with much better off axis frequency response, but they will not be available until 2007:

http://www.madisound.com/pdf/scanspeak/D3004_660000.pdf

The tweeter in the BM6P is a 28mm soft dome Esotec and the crossover is 12 dB/octave at 3100 Hz. Does anyone know the technical specs on the Dynaudio Esotec tweeters to compare them with the ScanSpeak or other tweeters to see if the impedances and sensitivities match well enough to try them?