I have Marantz SR4500 and 5.1 suround speakers. All the speakers are with wire connectors so the suround back speakers go to the s.suround speaker B terminals. The problem is when I try to configure the marantz: I go to Menu-Speakers. Now when I set the SL$SR(suround left $ right) to none I can,t select the SB(suround back)speakers. SO, its either 7 speakers or 3. What do I do?