This application relates to a systems and methods for enhanced dynamics processing of streaming audio by source separation and remixing for hearing assistance devices, according to one example. In one embodiment, an external streaming audio device processes sources isolated from an audio signal using source separation, and mixes the resulting signals back into the unprocessed audio signal to enhance individual sources while minimizing audible artifacts. Variations of the present system use source separation in a side chain to guide processing of a composite audio signal.