SKy Plus No Audio Pace TDS470n NOT SCART?

Hi Folks
Bit bemused as to why I have lost all audio from my Sky plus box (Pace TDS470N 80gb)
I have tried different scart leads, an optical cable in to my Surround system and even the coaxial cable into the tv aerial socket and just have no sound anywhere but picture is fine.
I have gone into settings and volume is up.
I read on here about updating software and the factory reset and have tried both.
I am now at wits end and any help would be most appreciated
Regards
Jason