I have finally made up my mind to go with the M&K S-150 TXH system. I have a 350 sub and I am going to add a SVS PB12 plus 2 sub. I decided to upgrade to a 7.1 system and I have to figure out what speaker to buy for the rear surrounds. I am using M&Ks SS-150 dipole surrounds for the left and right surrounds. I am going to go with a much cheaper solution for the rear surrounds but I don't know if I should go with another dipole or direct radiating speakers. Also, the S-150s are 4 ohm speakers. Do I absolutely have to go with a 4 ohm speaker or can I use a decent 8 ohm satallite speaker? Thanks for the help.