[Darryl Ramm]

I would expect setting the Buffer size in Logic Pro is all that is required. Logic Pro makes exactly the same CoreAudio request to the HAL/driver to change the HW buffer size as Audio Midi setup does. I have trouble seeing how else any of this could possibly work and I have some understanding of Core Audio internals.

Sure if nothing is using the interface it might show some default buffer size, but changing that in audio midi setup should not be needed.