I'm thinking of upgrading from my old Yamaha A5 to either the 750 or 756 (Anyone know the spec difference for these two as they appear to be very similar in price. Obviously the 756 is the latest model but is there any big advantages?). Anyone have any experience with either ? The A5 is a great little amp for the price so I'm hoping the upgrade will be good aswell. Since the newer models support 6.1 I'll need to get a rear center speaker. Anyone have any suggestions that won't break the bank? I currently have the BOSE Acoustimass 15 which doesn't support 6.1 and since I don't have the cash to upgrade to the 16 ? range which does support 6.1 I thought I could just add another speak to the extra channel on the new amp. Should I just buy another double cude BOSE to keep the range all the same or is there another one somebody could suggest. As always any and all help or suggestions are greatly apprecaited.