I HAVE A ADCOM GFA7700 5.1 AMP,[150WATTS].I'M LOOKING TO GET A SET OF SURROUND SPEAKERS,GIVING ME 7.1 SYSTEM.THE SURROUNDS WILL NOT BE POWERED.MY QUESTION IS,DO I HAVE TO USE ALL CHANNELS ON MY GFA7700? CAN I JUST USE IT FOR MY MAINS AND CENTER? WILL THIS GIVE ME MORE POWER?I WOULD LIKE TO DO THIS AND MAYBE GET SOME OF THESE 200'S FOR MY OTHER SPEAKERS.OR MAYBE SOMEONES GOT A BETTER IDEA? THANKS