Bass boost is no more dangerous than the bass control on your HU or equalizer. In fact they do exactly the same thing, except that the boost control only affects the sub amp. The key is to set your sub amp gain with the control at full boost, so it can only be used to turn the bass down not up. No clipping, no distortion, no problem.
You are half right. Yes, you can set your gain with the bass boost at full, and avoid clipping. But then you are loosing a lot of output (up to 18 db's) at all freqs other than where the bass boost operates. Bass boost is in no way a good thing, to be completely frank.
Gain attenuators means when set on maximum, they allow the full current draw/pass of your amplifier at whatever gain setting you have it at. So if you set your gain attenuator at full before setting the gain, you get all the benefits of a bass control knob, and none of the negatives of a 'boosted' signal in a very limited bandwidth. Bass boost
sucks, gain attenuators are very useful.
Clipping is a bad thing for one main reason. Imagine what a sine wave looks like. Its a line that deviates from the zero position, oscillates to one extent, and then reverts back to zero and extends to the opposite extent, before finally returning to zero (one full sine wave). The area under the wave (the space between the sine wave and the zero point line) is a visual representation of the power being produced. How far the sine wave deviates from the zero line represents amplitude. The problem with a squared wave is, the area under the sine wave gets larger, while the amplitude does not increase, creating that plateau or flat spot in the wave form. This means you are increasing power to the speaker, but the amplitude is not increasing. So more power is going to the speaker, but the cone is not moving any further. That added power is completely wasted in terms of output produced (again because the cone excursion does not increase), but the speaker must still dissipate the extra heat generated from that added power. This is exactly why clipping, a squared wave, tends to create thermal failure in speakers.
But, keep in mind, its not the squared wave form itself that causes damage, its the heat from the added power. So if you hook a 100 watt amp to a 1000 watt speaker, and clip the hell out of the amp, the speaker will still remain safe, because its capable of handling more than enough power to compensate for the clipped 100 watt amp. I only say this because a lot of people tend to think distortion, in and of itself, somehow damages speakers. A speaker doesn't care if its reproducing distortion (a squared wave) or not. In fact, it has no idea its reproducing distortion. To the speaker, that distortion is simply another part of the signal it is expected to reproduce.
Hope this helps.
