If I understand your question, you would like to hook up 3 pairs of speakers to one output (the surround back amps which will be unused in your 5.1 system) at the same time. You are wondering if this is possible given a switcher rated for 4 ohms, and an amplifier rated at 6 ohm minimum. If this is your question, here is the answer. It depends how you hhok them up. Resistence is calculated differently depending on if you hook up the speakers in SERIES or in PARALLEL. In a series hook up, the resistence is cumulative. That means that if you have 3 sets of 8 ohm speakers hooked together, you will end up with a 24 ohm load, and your receivers output will be very limited. If you hook them all up in parallel, you will end up with a load that looks like this to your amp (1/8+1/8+1/8 = 3/8 = about a 3.7 ohm load. That would likely be not so ideal either. There is a thing on the market out there somewhere called a resistence stablizing speaker switcher or the like that will allow you to hook up multiple sets of speakers, and maintain a normal (8 ohm or so) load. I'd check into one of those. For greater info on the connections of series and parallel, type it into a search engine (google or yahoo) and you will be able to find diagrams that explain them better and easier than I will be able to by using words.
