I know you can activate Shrunken head before channeling the ultimate to prevent most interrupts (there are a few superior magic stuns though).
But what about Assassin's Shroud? Can it be used immediately before/after activating the ult to be invisible?
What about the Void Talisman, can it be activated while channeling without interrupting?
I guess that would be another way to reword the primary question. What items can be activated without breaking channeling?