You wont be "pushing" the sdc with 600rms. Ive given mine 1500 for 10+min and theyre fine, they get smelly after about 30 min, but Ive done it many times with em in the 2 years Ive had them. Give it a thousand!!
what i was getting at is that two 15s normally draw more power than one 10 or 12. bigger magnets take more power to energize. not exactly always true but you get the point. that amp is badass and at $90 its a steal i wish i could find one that cheap.