Hi @mwatsme
These are some pretty cool designs. I've seen up to 8 channels on a single DAC chip, and all of them run in parallel. The answer is all channels get the same input and the output is averaged. I think I've even seen them run in differential mode. That is, 4 channels do + and 4 do -
In all cases the idea is that any manufacturing errors get averaged out. If you not only run in parallel but also differential you get even a better chance of reducing errors due to manufacturing.

