The application discloses a system and method for playback of audio signals though a large variety of headphone devices. To optimize playback, the specific headphone device is identified so the proper amplifier gain and equalization settings can be applied. Such identification is determined by measuring the headphone impedance as a function of frequency, and comparing the impedance data with data of know devices in a database. Once a match is found, the appropriate audio gain and equalization settings can be applied.