Hi, guys. Just two brief questions. A few months back I bought a Yamaha HTiB-40. It's a very good system, but I've noticed two things: First, (and I'm really showing how much a novice I am with this!), I thought the rear speakers are only for low frequency sounds; presently most of the sounds seem to be bleeding through to the rears. Is this okay, or do I need to adjust the amp? Second, there is a noticable amount of hiss from the rears at high volumns; is this characteristic of the Yamaha amp or again is it a dodgy set-up. Thanks in advance for any advise you may have.