Hey,
First thing i noticed on images on the internet that the pro 14 has no lightpipe and thus not able to connect to your octopre le.
Basically what you need is a sapphire with adat input / output.
The pro 24 dsp has a lightpipe in and can only recieve audio so you will not be able to use the LE outputs.
So i guess you have to look in the higher range. The 40 could be a good choice choice.
You will have more than enough channels.
Will it run smoothly? I think so... Only Simon/dave of focusrite can answer that.
I believe the sapphire 40 accepts firewire instead of usb. Perhaps unnecessary information but ......
Myself run almost the same setup only the 40 is a scarlett 18i20 and the LE is a octopre dynamic.
- Angelie
Adat lightpipe is compatible but keep in mind that some of the sapphires have 2 adat in and support 8 tracks @ 44/48k and only 4 tracks @ 96k. So if you use higher sample rates you will loose 4 tracks of the LE.
Ending up with 12 xlr inputs @ 96k