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To what are you connecting the speakers? If it is a PC with surround sound, then you might be able to connect one of the 2.1 set-ups to the front left/right connection and the other 2.1 set-up to the rear left/right connection. If your speakers have a separate sub input, let us know. Otherwise, you'd want to set up your software for a 4.0 system, or a 4.1 system with no bass going to the subwoofer output (because your speaker systems would be handling the direction of bass to their own subs).