It's labeled subwoofer in the pre-outs section of the 2802. All speakers set to small. The speakers can handle different crossover points to the sub. Unfortunately, the 2802 uses global bass management with XO points at 80/100/120 Hz. Normally you'd set it to the highest requirement of the speakers, in this case the RM2300s which need 120Hz or higher. You could try 100 Hz, but there is a chance of blowing the 3.5" drivers.