A digital equalizer (EQ) is a processor-based device that augments the sound of an audio signal in an audiophile or home theater system.

Digital EQs are found in subwoofers, AV receivers, AV preamps and many other AV components.

Digital EQs can be simple, with boosts or cuts to certain frequencies, or more elaborate incorporating data from the acoustics of the room to create a multi-step EQ curve that helps make a room sound more accurate. Examples of the latter are Anthem Room Correction (ARC), Audyssey, and Trinnov room correction. Audyssey MultEQ room correction software is found in many receivers from companies like Denon and Marantz.