raspy high end

I am driving a new pair of kef xq40 with a vintage yamaha m2 amp (240 wpc) and a matched yamaha c-4 preamp. Using a jvc dvd player and playing hd recodings. The sound is full round and ALMOST PERFECT. I am biwired with flat 14 g cable. I am hearing a raspyness in the high end... almost as if blown tweeters but they are not.... it is minimal but needs to go! Ideas?