Bitte gerne I have another idea on this topic, maybe it also fits into your planning / setup, now that you are considering using external PCIe enclosures.
I don't know your setup exactly, but you seem to have some MADI devices in use and devices like the M32 Pro with its 32 channels at double speed already occupy a complete MADI bus (inputs or outputs depending on the model, AD or DA).
With the amount of channels needed in MADI, such a PCIe expansion enclosure would also allow you to consider the HDSPe MADI FX card. The PCIe 390ch card offers three MADI busses (2x optical, 1x coaxial). With the optionally available daughter card HDSPe OPTO-X, the third bus can also be configured optically.
The interesting thing about this card, apart from the number of channels, is the special resource-saving driver that does not keep all channels permanently active. It groups all channels in groups of 8. Computer resources from driver are only occupied if at least one channel in such a group is active in the DAW. With clever use of the channels, this reduces the load on the computer caused by the driver.
The other features of this card are also very interesting: analogue I/O for headphones, Word Clock, MIDI I/O, MIDI over MADI, FX chip, AES interface. The AES interface could be used e.g. to directly connect an ADI-2 Pro FS R BE for monitoring via speakers or headphones and using the special ADI-2 Pro features.
One application of such a card with 3 MADI busses is also, to be able to distribute the devices according to the type of remote control that you are doing. You might know / remember, that "Auxdevice" and "MIDI remote" can not be used at the same time on one a MADI bus. By the three MADI busses you can put e.g. preamps with Auxdevice support on MADI Bus1, devices requiring MIDI remote to MADI bus 2 and other devices that need a lot of I/O channels like the M-32 you could connect to MADI bus 3 (they are remote controllable via Ethernet) so on that bus you are free to connect any other type of device if there are still channels free and use either Auxdevice or MIDI remote.
Just an idea. Its a fine card, you can see my review here: https://www.tonstudio-forum.de/blog/ind … Pro-FS-BE/
BR Ramses - UFX III, 12Mic, XTC, ADI-2 Pro FS R BE, RayDAT, X10SRi-F, E5-1680v4, Win10Pro22H2, Cub13