Hi framer2180,

The tonal matching of the QS4s and QS8s is extremely close. The '8s have larger woofers for greater power handling in bigger rooms, so consider how large your new room will be if you are planning on adding a second pair of the QS series. Definitely use the QS8s at the sides as your "main" surrounds and move the QS4s to the rear for 7.1.

Regards,

Alan Lofft,
Axiom Resident Expert (Retired)