Logitech Z-5500 - what happens with 2 channel audio sources?

[cancancan]

HI there

I've ordered some Logitech Z-5500 5.1 speakers ( http://www.logitech.com/index.cfm/speakers_audio/home_pc_speakers/devices/224&cl=gb,en )

but I am wondering - if I connect the optical output of my computer (Apple G5 Powermac) to this speaker system and play things like music from iTunes or other 2 channel audio.....how will this be translated by the 5 Logitech speakers & sub ? Will there only be audio from 2 speakers? or from all of them?

 

[bugser]

Hi, i have z-5450 http://www.logitech.com/index.cfm/speakers_audio/home_pc_speakers/devices/229&cl=gb,en

music can be played from all speakers dolby prologic 2, or stereo, or stereo x2 which is left & right back and front
the stereo source gets upmixed by the decoder to your choice