I bought 2, one for the front and one for the back. They are two separate speaker systems and needed two separate equalizers. Each has a fader ctrl for fine tuning and a separate subwoofer slider for future expansion. Prob not the most modern sleek look but I keep them in the trunk in a slot for a CD Changer (remember those?) If you consider the price, two of these are still way cheaper than a 4 channel equalizer. No noise issues. Works well. Very happy!