Hi Joe,
I have the YST-MS50's hooked up to my 9000pro. They came with the board otherwise I might have been tempted to go for something else BUT they are very good quality.

Even at quite high volumes there is no distortion provided you don't go too mad with the bass on the sub. Better than a lot of other speakers I have had in the past.

If you want to know anything more specific then give me a shout
best wishes
Tony W

PS Dave:
Nice to see even you pro's practice your scales (I know.....so weak!)