If you want to use an older Pro Tools interface such as a 192 or 96 I/O with Pro Tools then you may find yourself scratching your head as you try and make them work.
In our tests neither Pro Tools 10 or Pro Tools 11 will see a second interface when connected to the Expansion port on the Avid Omni interface, we were using Pro Tools HD Driver v11.0.1 for Mac, but when the second interface is connected to the card directly they appear within the hardware and I/O configurations. We do not seem to be able to find any documentation either confirming this is expected behaviour or a bug. We also tried connecting first to the 96 I/O and then to the Omni and as we expected this did not work either.
Mike also had an extensive conversation with Avid and another community member who had equally puzzling behaviour when trying to connect Avid Omni and MADI HD interfaces to a HD Native card. He was told that using 2 MADI interfaces and an Omni is not one of the configutations Avid test, so although the planned configuration wouldn’t have gone over the number of I/O, Avid could not be sure it would work.
So if you wish to extend an Avid Omni by adding another interface, then you will need to connect it directly to the second port on your card - unless of course other community members have had success where we have not? Discuss.