In various applications, the system provides a method for processing audio signals, including: receiving a request for audio content; receiving an identifier encoded in a personal audio device comprising a transducer for playing audio; retrieving at least one parameter associated with the identifier; and processing the audio content using at least the request, the identifier and the at least one parameter, wherein the processing is customized for the personal audio device based on the at least one parameter associated with the identifier. In various applications the parameter is, one or more of, associated with a specification of the personal audio device, acoustic metrics of the transducer, relates to control of equalization, relates to permission to enable proprietary sonic processing for enhanced acoustic reception of streaming content, relates to acoustic metrics of the transducer and wherein the identifier is associated with permission to enable proprietary sonic processing for enhanced acoustic reception of streaming content, and/or is stored in a chip on the personal audio device, is retrieved from a server in a network, among other things. In various applications, the personal audio device comprises ear buds and the identifier is stored in a non-volatile memory of the ear buds.