> Is special software necessary when using Dante and/or MADI?
MADI interfaces come with their own software to handle the routing. RME's MADI interfaces use TotalMix. https://www.rme-audio.de/totalmix-fx.html
Dante interfaces all use Audinate's software to handle the routing: https://www.audinate.com/learning/technical-documentation
> I assume that would be necessary since my UAD audio interface is Thunderbolt based. First of all, I suppose I should have a go doing that with H9000's USB I/O.
It would be necessary, yes. Relevant threads include https://www.eventideaudio.com/comment/40779#comment-40779 and https://www.eventideaudio.com/community/forum/rackmount/issue-h9000-mac-aggregate-device I should make a FAQ about this….