[_paralyzed_]

I have no idea what the sony puts out for power, it says 285 watts to the sub, but is that rms, or is it peak, or is it downhill with a tailwind? Regardless, if you want "more bass" I don't think you will hear much of an increase by simply putting more power to the kicker. It would definately be cleaner sounding. But, with a plate amp you could run the kicker and put the sony back in using the sony power. That should add some volume. And yes, it's perfectly ok to drive a 350wrms sub with a 500w amp. It's always better to have extra power or "headroom", just be sure when you set the output level that there is no audible distortion and you'll be fine.