I have a Rotel 5.1 receiver and wall mounted Magnapan speakers all the way around, including the center channel. Recently I noticed that I wasn't getting any rear sound. I'm using a coax cable for DTS. When running the Rotel tone check, the announcer voice and tone comes from the left, right and center front channels but not from the left and right rear channels. When using Sound & Visions test disk, the DTS tests for placement show all speakers responding with the correct placement! and the speaker level test also shows each speaker responding with the level test tone in sequence! However when I run the phase test, the rear speakers only respond to the out of phase tone, not the in phase tone. I tried reversing the speaker wires on both rear speakers, but without result, they still only respond to each test the same way. Anyone got any ideas what the problem could be?