I know this is probably a reciever setting issue but........ i'm hopefully looking for a quick diagnosis and some upgrade options. sony dn-1000 reciever, polk cs400 center, bose 201 fronts and (3) cambridge soundworks cs300s surrounds in a 12x10 room. want to keep my soundworks surrounds but want to upgrade to polk fronts and fix my sub problem. No red or green light and no sub sound easiest test for sub or best replacement if its dead. best replacement of front lt/rt for my setup. not too crazy its a small room but sounds great except for the sub problem now. any help on sub 1st and upgrades 2nd would be much appreciated.