You didn't describe your main speakers and amps or where the sub's going. With modest mains and amps, you might not need 300W of bass. And the bigger the room, the more power you need to feel the bass.
'Continuous' is the key word. Thumpa-thumpa (or oom-pa-pa if you prefer waltzes) is not continuous. But the 32 foot orgam pipe at the beginning of Also Sprach Zarathustra is C0 (16.35 Hz, 5 octaves below middle C) is continuous.
One main difference is, as in many things in this world, heat rejection. Oom-pa-pa gives the speaker time to dissipate the heat from the voice coil. Constant bass notes (20-120 Hz or so) don't allow that time.
Another difference is that the voice coil itself may not be able to handle the voltage or current and could 'flame out'. I'm sure some of you may have seen stage monitors do this at certain high-dB rock concerts. Impedance is not resistance, but they're close enough for these calculations. First, P is watts, I is current, V is volts; equations are P=I2R (I-squared) and P=IV. To reach 300W at 1 Ohm requires around 17V and 17A. At 8 Ohms, you need around 49V and 6A. Short peaks reach 1600W. At one ohm, you need 40A and 40V; at 8 ohms, you need 14A and 113V.
So it's a trade-off between voltage and current. Too much voltage and the voice-coil insulation might be insufficient, resulting in flame-out. Too much current and it could get too hot, melting stuff in the voice coil and flaming out. I suspect the latter is more likely to happen. If the impedance is too low, the amplifier might not be able to supply enough current and you will have distortion; if too high, the amp might not be able to supply enough voltage and, again, you will have distortion. Amplifiers most often like to see 4-16 ohms; but yours may be happy with lower impedances, judging from its specs.
Low frequencies require a *lot* more power then highs. (At WPI, we'd run 4-6 900-1200W amps for the low end, a few 300W for the midrange, and 45W for the tweeters.)
I would suggest you wire for 8 ohm and not turn the amp up to 11. If this provides a nice balance with your main amps, great. If not, re-wire to 2 ohms and turn the sub input down to achieve reasonable balance; turning it down will limit the continuous power fed to the subs.
If you're watching movies, use care in extended gunfights. The 'Expendables' battle in the airport is probably close to continuous. When Dad and I watched it, the amp got very warm and we felt the shotgun blasts in our chests, but we were probably still well under 300W continuous in the sub-100 Hz range. (He had those A-L 602As for decades and *never* knew they could be *that* loud.)
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