Feedback Issues

I just bought a brand new POD studio GX so that I could record myself and try out the guitar rig 3 software which has been on my computer for ages. After some trouble I got it all hooked up and the only problem that I'm having is with feedback. The GX forces me to use the line out that is located in the back of it, so I have to use headphones. Though I did manage to get past this problem using a dollar store 1/4 - 1/2 converter and plugged it straight into my amps input and set my amp to its clean channel. Unlike the headphones though, my amp produces insane feedback/screeching when dealing many of the distortion settings in guitar rig. I would really prefer using speakers over headphones so I was just wondering if there is any way to reduce or get rid of the screeching. I also have computer speakers, but they are 5.1 surround so I'm not sure how i would go about connecting them. I'm a noob with the guitar --> computer stuff so any help would be appreciated .

Hey Everyone!

Hi guys!

Shout-out from Toronto, Canada.

I found GMC quite a while ago but didn't get around to signing up until now.

I've been playing guitar for about 3 years, and play mostly hard rock/metal. Hoping to really advance my playing through the great lessons here. As for gear, I play my strat though a Fender SuperChamp XD.

Hope to see you all around,

Pranjal