I was messing around in the setup menu for my cable box and in the audio section it had options for mono, stereo, and stereo matrix. I picked stereo matrix because the description said this was for hooking up to outside recivers. My question is it also gave me the option of using highly compressed or lightly compressed. It did not give any info on what to choose. Ant ideas? The cable box is a motorola with digital out. My reciever is a keenwood Vr 507.