Hi, i have an older analog tv about 5 yrs. old, a dvd recorder with optical out, and 1996 Technics SA-DX950 with built in digital surround decoder (i don't know what that is). I just bought a Yamaha surround system today with sub, center, front, and surround speakers. I have 2 optical digital ins on my technics receiver. I can get SFC surround mode to work on all speakers, but when i switch to Pro Logic surround the center speaker is loud and the other 4 are barely on, what's going on?

In the receiver, there should be volume adjustments for each speaker. Either lower the center's volume or raise the others.

Refer to page 15 of the manual.
http://ec1.images-amazon.com/media/i3d/01/A/man-migrate/MANUAL000031492.pdf

I can get SFC surround mode to work on all speakers, but when i switch to Pro Logic surround the center speaker is loud and the other 4 are barely on, what's going on?
What's the audio source when this happens? And does it happen with other audio sources as well?