Almost every new Amilo has got an optical digital output. You can only use a 5.1 sound system if it has got a digital input.
The digital output is optical and uses the same jack as line out.
"City Cobra" describes his adapters etc here (German) and also in his x438 Sticky (German).
Other series should have got the same.
Alternatives
If you have a 5.1 sound system with an analog input, you need a PCMCIA- or USB-soundcard with same analog outputs. More informations here (German).
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The German equivalence to this Sticky can be found -> here. Die deutsche Version zu diesem "Sticky"-Thread findet ihr -> hier. (date: 09/12/2005)
date: 03/27/2006 by selfmade