sibilence....any cures out there?

I have recently accuired a pair of Nola Viper 1A speakers, while their performence is outstanding generally, the only problem is highlighted sibilence on vocals which is very annoying!!! Is this down to the speakers? Would a change of interconnects help? Any ideas from you guys would be appreciated greatly...
I ended up curing my system's with less toe-in and also interconnects. For me, interconnects were very frustrating and costly to evaluate and I feel extremely lucky I ended up with ones which mate perfectly with my system. Now I can listen to Diana Krall and Eva Cassidy "Live at Blues Alley" without being bothered by sibilance. YMMV.
Diana Krall has naturally sibilant singing style. If you don't hear Diana's sibilance the system may not be resolving enough.
swampdog, Jylee is on to something. What kind of music do you listen to? Some sibilance is natural. On rock and pop recordings I hear a lot of processing of female vocals. See Adele for recent example. WTF they do that for?
All Copper Cables !! A very simple but effective way to address this issue. Mostly sibilance is not a function of equipments unless they are horribly mismatched. It is more of a creation of associated accessories like Cables, bad power, isolation techniques etc. If you could start simple copper cables from Mogami it will tell you if it is a step in the right direction. Mogami makes very balanced sounding cables at sold at throw away prices so it will not cost you much. I had faced a similar issue long time back and it was my speaker cable at fault.