I need more outputs on Yamaha LS9-32 so I am looking for an interface to extend outputs via ADAT output. I have MY16-AT card in it.
If you're looking for an inexpensive option, you could go for 2x Behringer ADA8200.
Such two interfaces will allow you to use all 16 Ins and Outs on the MY16-AT.
I have worked extensively with the LS-9 and have used the optical ports to extend the inputs/outputs a few times. We had a an older MOTU 828 (mark 2 I think) that we used with good success with our LS-9. If you need 24 more outputs the 24A0 from MOTU may do the job but i dont remember what the mac you can connect to the LS-9 is.
I may be able to offer more if you can specify why you need the extra inputs.