Select Sat/Cable as default source

[x20mike]

Just bought a Sony BDV-E370.

Have connected sound inputs - Optical from my TV and Digital Coax from my Sky box.

I watch tv through Sky most of the time so need to select Sat/Cable as the Source input on the Sony Surround Sound system. I can do this manually and it works however every time I switch the Sony system on it defaults back to TV and I have to manually select the SAT/Cable sound input.

Is there anyway I can set the Sony system to default to Sat/Cable sound source so its correct when I switch on?

I've tried removing the optical cable from my TV but it makes no difference, it still defaults to TV even though there's no optical cable plugged in.