preventing clipping on amp

preventing clipping on amp

OK - my dad brought an oscilloscope home from work for me to use to tune the amp that's powering my sub. I realize it's all pretty fruitless giving the fact the speaker is 1200W max/300W RMS however my amp is only 300W max/ 200W RMS (all @ 4 ohms x 1 ch.) The Jensen amp I have is really a waste of time and just can't put out the power the sub is capable of handling, however I do have questions that might help me get the best out of what I have at the moment.

Port tuning is for 30hz (meaning that is the resonance frequences, I take it - the point where the voice coil impedence drops to its lowest). The amp features 40-400hz adjustable HP/LP Xover. What should I set the Xover point at? The speaker is rated 23-400hz response range.

The amp also has a 0-6dB bass boost circuit, which really doesn't make much difference until it's at 6dB or very close to it. Any idea what I should do with that...leave it alone or what?

Thanks,
Trav