It's an Onkyo theater in a box, don't know which one exactly but the reciever is the htr520 I think. Anyway, the suround sound is very hit or miss with it. For some reason, one day it will work perfectly, the next I'll only get sound coming out of the center channel. As soon as I put it on all channel stereo, all speakers work. Ive tested this with several sources, and would really like to get it to work consistently. Any help would be appreciated.