With a third box I could make the analog box power supply much more efficient (I’d use multiple switching power supplies with a lot of filtering both on the inputs and outputs and then more filtering in the analog box.)
There’s no technical advantage in having an external clock for consumer playback, that guarantee’s more jitter. When integrating into a music editing system or shop an external clock would be a good option. The analog box environment is clean enough to get excellent performance with a good local clock.
I don’t see any obvious splits for the digital box.
Looking at things a little differently I’d like to have the possibility of one digital box and, say, three analog boxes for a multichannel system. Some others would like the idea of using a digital box with a digital crossover and multiple analog boxes for a biamped or triamped system. I spent some time working on allowing this possibility with the initial TSS release, but I couldn’t come up with anything that wouldn’t compromise a simple two channel system so I reluctantly set those ideas aside.