hi there all you polkies.im new to home theater and must confess iam hooked! but here is my question,i have an onkyo txds 787 av reciever which is awesome and kicks u know what!!, also have polk speakers all around rt800ifronts cs400icenter fx300isurrounds for sides and rt15i for surround back channel. my question is my reciever is 7.1 compatible and it has preouts for external amp ,iwant to upgrade to this but want to know if i can hook up another onkyo or any other reciever to hook up my side surrounds and add a second speaker inthe back for 7.1 thus only leaving my onkyo to run my 2 fronts and center channels, can ido this and how do i hook all this up?also for the mean time is the polk rt15i a good choice for surround back channel or should ilook to a speaker like cs245i or something else to put as back speaker till i uprade to 7.1 please i need info from all you smart audiophiles out there ..and by the way i love my polk speakers the are the best they rule!!!!!