6ch vs. 2ch audio?
 

For dvd movies whats the difference?

Wrong board. Anyways, 6 channel is surround sound(2 front speakers, a center speaker, 2 rear speakers, and a sub) 2 channel is basic stereo.

sorry and thnx

Is that not dolby 5.1???
what's the difference between surround and 5.1?

6 channel and 5.1 are the same thing. The .1 is the sub. Instead of calling the sub another channel some call it .1, therefore you have 5.1, or 6 if you want to call the sub another channel. 5.1/6(whatever you want to call it) IS surround sound.

So if i backup a movie and only keep the 2 channel audio then put my reciever on stereo when i watch the movie my sub wont work?

It will work but it won't be the same as surround.

On surround mode with 2 ch audio will the rear speakers make any sound?

No, just the front 2 speakers.