I dont need a super loud volume, tinnitus is a scary thing.

I do however need great clear sound, flat, good soundstage, no struggle in the sound, to mix properly.

I have read that most USB interfaces can't deal with the 600 ohm headphones and I would need an additional headphone amp so I was worried this was the case too with the Babyface Pro.

And if you have strong requirements to get excellent sound go ADI-2 Pro

which also could support your ears by slow  ramp up of volume when connecting phones or switching channels.

In areas where you have tinnitus the PEQ could boost the frequencies near the Tinnitus tones a bit as people report to hear bad in that frequency range.

The ADI-2 PRO even supports 5 band PEQ for left and right separately which is good as you might not have same frequencies on both ears.

If you add these medical aspects and the quality plus dynamic loudness then the ADI-2 Pro is worth every Penny.

See manual and usually product Webpage,  but I have doubts that the pure data will tell you the final result how it will sound.
You should better compare the devices side by side.

I suspect it'll be enough but it also depends on the dynamic range of the material you're working with.  For example, if we're mixing pop it's much louder than recording classical, when we need to leave enough headroom across all the input channels.

Higher impedance tends to be improve the sound of headphones (transients) but it's pretty marginal.

Re the ADI-2 Pro and tinnitus, what design steps have RME taken to protect our hearing other than the slow ramp up when plugging in?  What are the chances of the digital volume control failing, particularly in "Extreme Power" mode?