I'm a little confused with most of these. If you run them in 7.1 mode can you use a external amp to power the 2nd room and listen to a sencond audio source? If so, is it more benefical to us a second same wattage amp for the second room source or just use the first amp in 5.1 mode using it's extra amp for the second room? Amp I thinking of is Denon AVR-1908 & using my old Yamaha RX-V850 as a second amp.