HPF - High Pass Filter - these babies can remove low end below a certain point to save your speakers.
A simple way to maximize headroom; reduce the low end content on your amp. Between the 30hz and 80hz zone especially. Your bass knob can go to the left!
If you have EQ sliders, even better. Going as high as 150hz to start reducing is not a bad idea either. The resulting tone may not be the greatest to your ears, but you will be able to maximize the headroom of your setup. Don't use bass boost controls off of your bass guitar and watch how you set the controls on your amp. Read the manual and figure out how to reduce the amount of low end you are using.