Systems and methods to process a digital audio broadcast signal having a plurality of digital audio signals can be implemented in a variety of applications. The digital audio broadcast signal having a main program service and a set of supplemental program services can be received at a digital audio system and processed to provide an audio signal to a set of speakers. The processing can include calculation of audio levels of audio signals of the main program service and the supplemental program services. One of the services can be selected with the audio signal of the selected service adjusted based on the calculated level of the selected service and a reference signal, prior to sending the audio signal to the set of speakers. In various embodiments, the reference signal can be an analog audio signal in the digital audio broadcast signal. Additional apparatus, systems, and methods are disclosed.