Great sound for six channels, all in one unit. Separate inputs and equalization for front, rear, and subwoofer speakers. The EQS has seven bands of full and half octave equalization control for the front and rear plus six, one-third octave equalization bands for maximum bass control. Add to that the Programmable Frequency Match (PFM) filter and a low output impedance line driver and you get maximum output and sonic clarity everywhere in the car. And to easily use a factory head unit, the EQS has built-in speaker level inputs. Truly a product for those who consider perfection possible.