Anytime you run subs you will want to run them in low pass. Signal processors are for more manipulation over the system they allow you to choose a certain frequency & either boost or cut it depending on what it needs. Mono block amps are used for subs only they are usually D class amps & are more efficient than class ab amps but do not have as great of a dampening factor. Class ab 2 & 4 channel amps are used for mids & highs they are not as efficient as the d class amp but have much greater dampening. The CVR model speakers are subwoofers. Let me know if you have anymore questions