My Yamaha A5 has started doing something odd. Analogue sound comes from the TV outputs (so it switches with source) and goes to the analogue DVD input on the amp. The DVD player's co-ax output is connected to the amp's co-ax DVD input so if the DVD player is in use it 'over rides' the analogue from the TV. The problem is I get no sub output from analogue inputs using Dolby Prologic on any input? If I set 'effect off' (disabling the centre and rears) then the sub comes to life. If I run a Dolby Digital or DTS DVD then the sub works. So the sub is working and the sub output of the amp works for analogue and digital inputs. I've tried using other inputs and the problem is the same. The bass management is set with all speakers small, sub output at 0dB (loudest) and Bass>Subwoofer. My only thought is the Prologic decoder has becme faulty but I don't even know if that's possible with DTS and DD are working. Any thoughts would be very welcome as I'm tried every menu setting and cable and can't see anything wrong. Can anyone suggest what's wrong or something else to try?