lm3875 chipamp and tube pre loud buzzing
 

Hi all,
Can you guys help me out?
Tried posting in the chipamp section, but no one had any ideas so i thought i would try here.
I have two chipamps and two ASL wave 8 monoblocks, running bi amped with a passive pre no problems. But when i try and use my Tube pre with the chipamps i get a very load buzzing through the speakers, the kind that makes you jump and hit the kill switch! This is the same if i just the tube pre and chipamps, no bi amping.
My aim was to run the tube pre + lm3875 for woofers + wave 8's for the tweeters.
Is this possible and what should i check?
All the tube kit is branded AV Reavox but its the same as asl i believe?

Many Thanks

Ian