I also don't think mixing PCM streams in hw would bring much added value. However the initial post mentioned that the DSP can handle decoders as well. That's a completely different story. If you have compressed streams, you could benefit from offloading the decompression and mix to the DSP. The problem is these streams are not controlled by PulseAudio/ALSA...You will have to go through a series of hoops to make this work, and some use cases will force you to provide the PCM back to the host anyway (think BT/USB playback). - Pierre
