SPDIF decoder/change audio port in windows?
 

I got some Logitech X530 speakers which has 3x3.5mm connections for the inputs. Now I want to connect it to my laptop, which has 2x3.5mm jacks, and one also outputs SPDIF. Now can someone recommend me a cheap SPDIF decoder that I can hook to these speakers? All the ones I've found mentioned online aren't made anymore and have way too many features anyways.

If I can't do this easily, is there a program or something I can run in Windows to change the second 3.5mm/SPDIF port to output the rear 2 channels instead of just being a duplicate of the front channels?

This is all on an HP dv6000 (6424ca IIRC)

noone? the only SPDIF converters I can find on ebay cost $100 and don't even do what I want