1. Some car power amplifiers are specially designed to promote woofers, such as: Kenwood KAC-PS401M (14.4V, 4 ohms), maximum power 1200W x1. Built-in infrasound filter, eliminating the need for external filters.

2. Power amplifier with equalizer, such as: Sony XM-604EQX. The EQX is equipped with speakers with a 5-band equalizer, allowing you to adjust the tone according to personal preference or different cabin spaces. Each EQX series has 5 frequencies to choose from.

3. 5-channel power amplifiers, such as: Sony XM-405EQX, Kenwood KAC-859, etc., usually use 2-channel or 4-channel power amplifiers to drive the front and rear speakers. The woofer is driven by another power amplifier, which takes up too much area, and using a 5-channel power amplifier, one power amplifier can solve the problem.

4. Multiple X-card power amplifiers, such as Laifu punch 400.4. The unique X-card provides an almost infinite variety of crossover options for power amplifiers: high-pass, band-pass, low-pass, and even super-audio filters. It can play a role of one to ten.

5. Electronic crossover modular power amplifier, such as: KICKER ZR360. These control blocks allow you to choose which signal will go to the power amplifier and to the RCA output of the power amplifier, select the desired frequency and crossover point. By changing the module, one power amplifier can be changed into a variety of power amplifiers.