Be a Professional & Certified Sound Engineer
Regardless of whether you are using active speakers or passive speakers with an amplifier, you should invest in a speaker processor. In my opinion, it is the most important piece of gear and will save you time, money, and headaches.
A speaker processor combines a number of processors into a rackmount signal processor. You will find gain, EQ, delay, crossovers, and limiting for both input and output.
A typical processor might have a stereo input and six outputs. The inputs will feature a 6- to 8-band parametric EQ and/or a graphic EQ, as well as a system delay. Each output on your processor will offer gain, a 4-band parametric EQ, a delay for time-aligning speaker components in a bi-amp or tri-amp application, or a full-range speaker and a subwoofer.