Try this:

Feed the sub the left and right channels. Do not run the sat speakers from the sub ...wire them from the speaker terminals on the amp.

Subs can be different in how they are wired to the satellite speakers. Usually if the satellites are wired from the sub there will be speaker lead inputs and outputs ...but not always. I have a sat system I can either wire the sub separate from the speaker outputs ...like I gave you here ...or I can wire the sats from the sub. Just depends on the speaker system.

When you wire speakers you want to make sure to observe "polarity" ...all the speakers are connected the same way. You'll see the red/black colors and sometimes just (+)/(-) or sometimes both. Look at your speaker wire. It'll be marked with either a white line or cast in ridges on the insulation of one of the wires ...the other will have no line or ridges. Pick the wire you will call "red" or (+) and wire the red/+ terminals on the amp and speaker using the designated red/+ wire. Obviously the other wire is used to hook up the black/- terminals. Make sure the ends of the wires are twisted tight. Make sure there aren't any stray "hairs" of wire that can cause a short when you insert them into the connectors on the amp and speakers. The point of all this attention to the wiring is so the speakers all work in phase ...they are all moving in and out in relative unison to the audio signal. If you wire one of the speakers backwards it will still play and you'll still hear music but one speaker will be out of phase with the other. You'll notice the stereo image gets funky ...like you can't tell the drums are at left center and the singer is stage center. Try it one time so you can hear what it sounds like.

Hope this helps and good luck with your setup :)