I am on the verge of buying an HTR-5760 but I have some questions about the presence speakers that I cannot seem to find any information on at all............ 1) How is the content that is sent to the presence channels actually determined? Is there some additional processing engaged when they are turned on or do they just share the same signal as the main L and R speakers? 2) How are these 2 additional speakers powered? The reciever is rated as having only 7 channels of amplification. So are there 2 additional smaller amps in the reciever that power the 2 presence speakers or do they share a portion with some of the other speakers? 3) If there is additional channels in the reciever or they do share power, then how much power is actually being sent to these 2 channels? 4) Has anyone actually used these 2 channels or any 9.1 setup before? If so is there any actual benefit to using these 2 additional channels? Any help with these questions would be greatly appriciated!! Thanks!!