Dave,
Have been working with Al for about 6 years to get it this far. Other user inputs I get are fed to him as well.
I asked for the hardware DAC volume control capability awhile back. Phase one comes in RevD. The uC they are using is good for a lot of things, so now a possibility, like Bluetooth or IR as future upgrades. Now, it is convincing Al what capabilities to add.
Originally, this was an internal only product for speaker systems not DIY. Program it once and done forever, no controls and no USB for audio file replay. I asked for the external chassis version with those capabilities and got it 2 years ago that started with RevC.
I think of this product as a DEQX HDP-5 with more channel capability and less than 1/3 the price. Really like the more flexible PC interface, and that is why I build these for folks for their specific speaker. I support the ones I sell and preconfigure the MS-3 and dspMusik system to make sure the user is up and running with their system quickly. That is the part that just buying a dspMusik directly does not provide.
For folks that know DSP, it is pretty easy. For folks that do not, it can be very difficult. Then add on top knowing how to do the electrical and acoustic speaker measurements for designs that require a custom version.
Will be interesting to hear what happens with the RevD system when it is finished.