I am having an issue. I have an old, old Sony receiver amp. It does not have a dedicated subwoofer port, so I currently have an 8" sub hooked up to its "center". I do a lot of movie watching, and I have to go to "phantom" setting (everything but center) because the sub doesn't do well with voices. Now, I dont want a center speaker. I listen to my music, and I listen to it LOUD and proud, and with the sub switched on it takes some of the pressure off the other 6 channels. I found a way to run a powered Logitech 2.1 system to my "center" channel wires and get a sub AND mid-range for center. The only problem, the Logitech has a ground wire and without that touching L or R the 2.1 system gives off a lot of hum and feed back. Now, if you touch the ground to either channel that mid-ranged speaker will work and the sub will, but the other speaker won't work. The amp doesn't have a ground wire, only left and right (of course). Could I go to radio shack and buy a female 3.5mm jack and wire it to the center left and right then wire the ground to the casing of the jack and expect both L and R speakers to work on the 2.1 powered logitech system?