Well either this has been covered extensively and I have missed it, or like so many many Apple topics no one want to stick their neck out. I am assuming that there are *forever* hidden buffers in ios and no drivers can be written past these. Too bad. I still would like some brave soul to come forward and say "it's this and this and this, and we can't get passed it, buy a PC, buy a "real" Mac....
Wade in oh brave audio geeks, put me out of my misery. Call me stupid, but inform my ignorance (-:

@peteppiano: I haven't seen any comparative measurements yet either, but I wouldn't worry so much about it and look at it from a different angle.

EDIT: found one here between Windows / ASIO and Apple / Core Audio: https://gearspace.com/board/music-compu … aster.html
Around 0,7ms more for Core Audio if those numbers are correct and assumed he means RTL (round trip latency).

The Babyface Pro FS is an excellent recording interface and has some design features that will benefit you in terms of low latency and all the nice features and option that a RME solution can give to you on the recording interface itself and in regards to additional features, drivers, software (TotalMix FX, DIGIcheck), excellend documentation and support.

1. there are very fast converters built in. You can have a look at this in my comparison Excel. There is nothing to complain about, on the contrary. See my blog article: https://www.tonstudio-forum.de/blog/Ent … B-MADIfac/
Direct link to the Excel: https://www.tonstudio-forum.de/attachme … 4-08-xlsx/
You find the values for converter latency in line 30 in samples @44.1kHz AD/DA.

The Babyface Pro FS manual details the latency values for each sample rate, the higher the sample rate, the lower the converter latency (as usual a little, not really much):
https://www.rme-audio.de/downloads/bface_pro_fs_d.pdf
https://www.rme-audio.de/downloads/bface_pro_fs_e.pdf
You find it in chapter 28.2, page 81.

2. RME does not rely on I/O chips from other manufacturers for communication with the computer, which cannot be changed in the event of a bug or poor performance. Instead, the communication via USB, Thunderbolt, Firewire is realised via the FPGA chip. In case of problems, firmware upgrades can be made. I personally wouldn't buy any unit anymore without such a worked out design. Together with the long term firmware/driver support that RME offers (for some devices nearly 22y) this is a real advantage for you.

I would like to summarise the whole thing in such a way that with RME you get an excellently designed quality product in terms of hardware (and also driver, software, manual, support) which is really worth every penny.

You only need to decide where you have your preferences.

The lowest latencies you will surely get with Windows, because ASIO drivers have direct access to the recording interface, they fully bypass the soundsystem of the computer.

I would get the Babyface Pro FS and connect it to Windows and Apple Systems.
This mobile interface is well suited to carry it to a friend or Apple Shop.
It is powered by the USB bus and then you can test your application / use case with it and finally choose the computer that fits best for you.