First off, forget "peak" or "max" power ratings on any amp...it's an irrelevant number. Assuming the sub is dual voice coil 4 ohms, you'll be able to wire everything up at 2ohms to achieve the 600w rms rating. And personally, I wouldn't waste my time on a second battery with only 600w, it's just not needed. If anything, simply upgrade your primary battery to an Optima red top.