I am looking for a way to get 16 synchronized audio output channels. Is it possible to synchronize 2 Tsunami boards to achieve this?
You could use a separate MCU to control them over i2c using a mux https://www.sparkfun.com/products/16784
It depends on what you mean by synchronized. If you just want them to be within a few milliseconds of each other, then you can either do what TS-Russell suggests, or if you’re using the trigger inputs, just connect the triggers in parallel. Because of the audio buffers and serial commands, there could be as much as 5 ms difference in start time between the two Tsumamis.
But if you mean precise, sample synchronization, then no. Tsunami has a feature called Synced Set which allows a single trigger to start from 2 to 8 tracks routed to different outputs with each track starting and maintaining sample-synchronization. But because each Tsunami is running on an independent crystal and the processors are not in sync with each other, there’s no way to get two Tsunamis to be in sample-sync with each other.