My first question would be what new feature in OSX 10.13 is so important that you will actually spend money on a new interface in order to keep 10.13?
Now upgrading is all well and good!
But that's my first question since rolling back to whatever version of OSX that supports your hardware is free.
Not sure if you meant to describe a pci thunderbolt adapter card or a thunderbolt audio 'interface' there. (Some people call interfaces "cards" regardless of the connection type.) If you meant a TB pci adapter though, none of them are recommended! It's more of a low throughput adapter to allow connecting modern TB devices that just happen to use the connector type. Anything requiring TB speeds doesn't play well with these. That's the review of every single TB expansion card I've ever seen unfortunately. Someone can feel free to debunk that of course!