Where's the sub crossover set (both in the receiver and on the sub itself)?

Do double check that all of the drivers in the M80s are operating (stick yer ear up against them). If the woofers aren't going, then check the straps on the binding posts.

I have to agree with everyone else about the T brackets--they work quite well if you use them properly--and you don't really need banana plugs on your surrounds if you're not going to be swapping them out all the time.

I am the Doctor, and THIS... is my SPOON!