From what I've read elsewhere on the subject, the front and side walls should be hard surfaces (the sides being as symmetrical as possible, i.e. bookshelves etc) and the back wall should be damped or softened.

I think I really need to do somthing with my back wall, things get harsh in here at higher volumes. Might just find me a bear skin rug to hang on the wall.

M60s, VP150, QS8s(3), SVS PB12-isd, Denon 3805, Emotiva UPA-7