Yup, can confirm that this is the case: 48 kHz only
I've now set it up so that the monitors are hooked up via USB-C, and the sub via the headphone output of the Macbook. Filtering I do in Element. It seems to work pretty well, but I seem to be losing a lot of gain somewhere though... Looks like it's the Aggregate Audio device for some reason. Edit: found my gain issues, they were hidden in the MIDI control panel.
A few to-do's though: I used a 3.5 mm to TRS, and the gain seems to be way too low, so I'll change to a 3.5mm to RCA. Also, I still need to add some damping to my workspace, which I hope I can do this week. And, these things need some kind of stand or another way to raise them a bit. I'll probably just 3D print some small feet for this: raising the front by about 3 cm should be enough. Once done, I'll make some measurements and dial in Dirac. I may also try hooking it all up the analog way via the subwoofer.
For now, though, they sound excellent, especially with the subwoofer crossover in place.