DVD-A and SACD are 5.1 only, so you will not be missing anything with a 5.1 system. The only thing is, a lot of people prefer direct radiating speakers for the surround channels in DVD-A/SACD music. So what they do is they hook up the surround channels from the DVD player into the back surround channels (which are often direct radiators) of the Receiver and then the back surrounds are used instead of the side surrounds.
I personally use my Qs8's for DVD-A and it sounds fantastic, so do not think you have to have direct radiating surrounds for DVD-A/SACD. It is more of a preference, but I promise you the QS8's will not disappoint.
