I've got two yamaha NS-A570 tower speakers (min 10 max 140 watts) and two small speakers from a small stereo system that i want to hook up to make somewhat of a surround sound theme. its obviously no fancy project so can i just wire each speaker into the tv or do i need a reciever to power them. some have told me i need a reciever and some have told me that the speakers arent big enough to need one. so can i just take off the back of the tv and plug the speaker wires into the tv speaker leads??