No 5.1 in Wipeout

[freeair]

Got Wipeout as one of the free games but when I ran the audio test I get no rear speaker sound. When the test goes to left or right surround speaker my rear speakers are dead and the surround sound comes from the front L & R speakers.

Any clues?

I should add that a BRD does output full 5.1 and the amp I have the PS3 connected to outputs to the rear speakers.

Dave