I have these speakers from a while ago, and they still work fine, but I'm just tired of getting up to adjust the volume on the control pod. I'm on a tight budget so I can't afford a new speaker system, so I thought that maybe I could get an A/V receiver and hook these speakers to it.

So, Can the GMX D-5.1 satellites be used in an AV Receiver?

 Ok, so I bought a used Onkyo 7.1 receiver and connected the GMX speakers to them and they work fine.  They actually sound a lot better than using with the GMX system and there's no more hiss.  The only problem is that the subwoofer doesn't work.  I was kind of expecting this, since there is no subwoofer out option on the GMX D-5.1.  I tried connecting a coax cable from the SWS Link Out to the receiver, but that doesn't work. 

Is there any way of connecting the GMX D-5.1 subwoofer to the receiver? Or do I have to get a separate powered subwoofer?

 yeah that should work, do you have a picture of the back of your sub you can post?

Here's a picture of the back of the sub and the control pod.

 http://img23.imageshack.us/img23/350/dsc05141l.jpg

 from that picture, it looks like the control pod is what you would have to use. Go from your subwoofer output from your reciever and hook that up to the control pod which connects to the sub. The line out from the sub is used for outgoing signals not incoming so you might have some problems there. Anyways,try using your control pod to hook the two up and let me know what happens. 

I tried that already, but nothing comes out, even when turning the volume up.  I just bought a powered subwoofer, so I'm good already.  Although, I can always use a second subwoofer :)

Thanks for trying to help me!

These "all in one" systems don't work unless they are compleatly hookes up. What that means is you would need to trick the sub into thinking the satelites are hooked up to it. It's called a "dummy load".  http://en.wikipedia.org/wiki/Dummy_load