I bought the Yamaha YHT-300 Home theater system, and along with that I bought a pair of Yamaha NS-A100XT floorstanding speakers. I noticed the speakers were 6 ohms..is this a problem? What happens is when I turn the volume up more than halfway the system shuts itself down. I disconnected all the speakers, and left just the NS-A100XT's connected and it did the same thing..so then I disconnected those and connected the small speakers that came with the package, and I could turn those up all the way without the receiver shutting off. Do I have defective speakers or is the receiver just not meant to run those speakers?? Please help!!