\rHI Jesse:
You should have no problem connecting and driving the two pair of BOSE 151 SE off of Speaker A wired together in Parallel.
You have a couple of choices for the Sub woofer. You can look to connect a passive Sub woofer as long as it has a built in crossover. First I would recommend adding two OSD OM-SUB200. One for each pair of the BOSE 151 wired in line with the Sub. Then output Speaker A to one of the OM-SUB200's then connect the one pair of the BOSE 151 to the output of the first OM-SUB200. Then repeat the same to the Speaker B output to the second pair of BOSE 151 to the output of the second OM-Sub 200.The OM-SUB200 has an internal crossover that will provide the right low frequencies to the 8" passive sub woofer. You can also add our SMP-250 dedicated Sub woofer amplifier along with a passive sub that does not have or need a internal crossover since the crossover is built into the SMP-250 sub amplifier. The first option is a great value that will take advantage of the AMP300 output capability.
TS-2206\r