The Logic Off Topic list

I've noticed there is a lot of distortion coming from my speakers when 
I'm doing a mix in Logic but not in the headphones. I thought at first 
it was just something rattling but it is through the speakers. Although 
there is no clipping it sounds the same as clipping if I clip it 
intentionally. I'm using a Sony home theatre, 5 small speakers and a 
sub woofer. The headphones are attached to a TASCAM US-122 audio 
interface and not to the Sony. Is the Sony the wrong kind of audio 
equipment to use with Logic? It's only with Logic that I get the 
distortion.

Thanks,
Peter