Hi, I've recently added these to my system, and the results are fantastic! However, I find that if the sub is left on, and you then switch on the BFD, you get a huge THUMP from the sub, even though there is no signal present (ie nothing playing)? The connections are unbalanced, just normal sub cable from processor to BFD, then BFD to sub. Surely I don't have to leave the BFD on permanently. Any ideas?