As Jason J pointed out, the 7100's channels can be used for anything -- the seven speakers that the channels are labeled for, or most any other combination you could think of. If you have all seven speakers (left and right, center, surrounds, and two surround backs) and a passive (unpowered) sub, you would use all of the 7100's channels and need something else to drive the sub. The 7100 is a good amp, but most subs do better with amps intended purely for subwoofer use. For example, SVS makes a number of passive subs, and they sell several different amps which they recommend be used with them. Outlaw's Model 200 would probably do a good job as well, but the amps sold by Parts Express or SVS (and others) are designed specifically for that purpose. Do you have an existing passive sub that you plan to use with a 950/7100 combo? We might be able to offer more specific ideas if we know what you plan to use.

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