Playing audio through Raspberry Pi

My Raspberry Pi and my BBC Master both share a 32 inch TV screen.  The problem is that I wish to continue using my Pi as a media player whilst simultaneously working with the BBC microcomputer (which doesn't play media).  In its default setting the Raspberry Pi sends audio through the HDMI to the TV and so all is very quiet when I switch to the BBC computer on SCART.

The Pi has an audio output however nothing happens when you plug an audio jack in.

A little Linux is required:

    lsmod | grep snd_bcm2835


Followed by:

    amixer cset numid=3 1


(To return to the default settings change the final '1' to '2'.)

I can now use the Pi as a media player, whilst simultaneously using my BBC computer as a productivity machine.  My music media files are stored on an external hard drive on my home network.  Altogether I am a happy nerd.

I cannot, however, force the audio through the headphones audio jack when using RISCOS on the Raspberry Pi.  I have tried changing the config.txt file by following online instructions but so far have had no luck.  If anyone knows how to do this then please get in touch.