You can Coax sound out to on the bord you pictured its the orge plug beteen the PS2 ports and the USB ports on the bord. Looks like it has a platic dummy plug in it if you wan to use coav you will take the platic protector out.
Look on Kijiji fore an amp ?
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Logitech X-530 Computer Speakers System - Ottawa accessoires informatiques à vendre - Kijiji Ottawa