A portable audio amplifier for a portable audio device or musical instrument that includes an internal housing and an exchangeable external housing and exchangeable cover, as well as a storage compartment is described. The storage compartment, which is contained in the internal housing, may contain a cord and other audio accessories such as picks, batteries, adapters, or personal items. The storage compartment can be opened through various methods, including translation, swiveling, pivoting, or sliding of a cover. The amplifier's external housing and/or cover may be customized by the user after purchase using exchangeable elements. Exchangeable external housing options, which act like a skin for the amplifier, include both manufactured housings (designed specifically as an external housing for the audio amplifier) and repurposed housings (designed for a primary purpose other than audio amplification). An adaptive structure may be used to adapt the dimensions of the internal housing to a larger, external housing.