I have been driving a pair of NHT 3.3 with a pair of NHT SA3 amps on the subs and a 5 channel amp on the upper speakers and center , rears. I just purchased a Proceed Processor, it only has one sub output. I have two options; 1. Use an RCA splitter on the sub output 2. Use the built in x-overs in the SA3 Amps
RCA splitter and let the processor do the crossover at 100hz if I remember correctly. I used an EAD Signature with my NHT 3.3's with a monosub signal. Bi-amping those speakers really wakes them up. Using an EAD Powermaster 2000 with 500watts to the top and bottom on each side is really impressive.