Only getting half the sound through surround speakers

[moggleflop]

Hello,
I have Logitech x-540 speakers, and an external USB soundcard for my laptop.
I'm using windows 7 home premium.
For some reason the sound is only playing through the green 'front' speakers cable, I still get bass through the sub but half the speakers don't work and I'm only getting half of the sound- there are parts missing from songs. Its incredibly annoying, it worked ok before so I cant figure out whats gone wrong. Anyone got any ideas? thanks!

 

[ssddx]

most music is recorded in stereo (left and right channels).
the front 3.5mm port sends a signal to the left and right speakers (channels).
quite a coincidence!

unless you are playing surround sound songs or surround sound game/video audio i dont think there is anything wrong.

it is perfectly normal to hear your music on a surround system through just your sub and front speakers. now, you can change that in your audio properties to a different mode which causes the rear speakers to repeat the same audio as the front speakers but you aren't really "hearing more" just pushing it through more speakers.