A portable speaker system (100; 500; 600) for attachment to an electric string instrument, the portable speaker system comprising: a housing comprising: an audio jack for receiving an audio plug, the audio plug providing a raw audio signal generated by the electric string instrument; an amplifier coupled to the audio jack and configured to receive an audio signal and amplify the audio signal to generate an amplified audio signal, the audio signal comprising one of the raw audio signal and a processed raw audio signal; a speaker coupled to the amplifier and configured to receive the amplified audio signal and generate output sound from the amplified audio signal; and a power supply coupled to the amplifier and speaker for powering the amplifier and speaker; a button connector disposed on the housing, the button connector configured to receive a strap button of the electric string instrument, the strap button extending outward from a body of the electric string instrument, to attach the portable speaker system to the body of the electric string instrument; and a stabilizer extending from the housing for inhibiting rotation of the portable speaker system when the portable speaker system is attached to the electric string instrument; characterized by a mounting mechanism attached to the housing, the mounting mechanism including a holder for retaining a portable computing device therein, wherein the mounting mechanism is detachable from the housing. a housing comprising: an audio jack for receiving an audio plug, the audio plug providing a raw audio signal generated by the electric string instrument; an amplifier coupled to the audio jack and configured to receive an audio signal and amplify the audio signal to generate an amplified audio signal, the audio signal comprising one of the raw audio signal and a processed raw audio signal; a speaker coupled to the amplifier and configured to receive the amplified audio signal and generate output sound from the amplified audio signal; and a power supply coupled to the amplifier and speaker for powering the amplifier and speaker; an audio jack for receiving an audio plug, the audio plug providing a raw audio signal generated by the electric string instrument; an amplifier coupled to the audio jack and configured to receive an audio signal and amplify the audio signal to generate an amplified audio signal, the audio signal comprising one of the raw audio signal and a processed raw audio signal; a speaker coupled to the amplifier and configured to receive the amplified audio signal and generate output sound from the amplified audio signal; and a power supply coupled to the amplifier and speaker for powering the amplifier and speaker; a button connector disposed on the housing, the button connector configured to receive a strap button of the electric string instrument, the strap button extending outward from a body of the electric string instrument, to attach the portable speaker system to the body of the electric string instrument; and a stabilizer extending from the housing for inhibiting rotation of the portable speaker system when the portable speaker system is attached to the electric string instrument; characterized by a mounting mechanism attached to the housing, the mounting mechanism including a holder for retaining a portable computing device therein, wherein the mounting mechanism is detachable from the housing.