Richie,
Yes you are correct you are using only 2 channels for the four A & B speakers. It is really nice through to be able to run either the QS8's the M80ti's or all in combination. When playing SACD or DVD-A I usually use the 4 m80ti's plus the VP 150 when watching TV or a movie I usually run them all.
Lee

Axiom M80Ti(4) Axiom VP150(1) Axiom Qs8(4) Axiom M22ti(2) Axiom M3ti(2)