i currently have 2 sawm40 12" sony subs and my local bb has the sawm20 subs on sale clearance, im wondeirng whether i should buy the sawm 20 8" subs since theyre so cheap my room is strange, there are a lot of dead spots in my room, even with the 12 inch subs you dont hear it in my room unless youre within a few feet of direct fire. my room is about 15'x15' its small yet bass dissipates very quickly in it. its pretty empty in my room. im wondering if i should get two more 8" subs to help increase the size of the sweet spot? since i dont know anything about cancelation and all that technical mumbo jumbo, what should i do? will getting 2 more 8" subs help strengthen the bass? or am i being too greedy?