leonardo wrote:… connecting directly or with a hub makes no difference whatsoever, …
In this case one hub was defective as I understand.
I have an iMac M1 with Sonoma 14.2.1 and am using a now nearly 20 years old Fireface 800 connected without a hub (but of coures the adpater daisychain). There are no glitches and I didn't have glitches with these machines before with earlier MacOS.
I switched to Apple in 2021. Though I had been using Apple only privately and my whole professional life for other purposes (graphic design) I had to start hard disc recording with a Windows environment because of compatibility with some studio. First on Digidesign Session 8 with a connected ADAT in the early 90s which was pain in the ass most of the time. Then in the 2000s I switched to RME and Cubase still on Windows. I had a new high end machine configured by a studio supplier and they recommended the RME Fireface 800 which I bought. But there was always something wrong. Soon the motherboard died on the PC and there were always problems with synchronizing audio and midi, bluescreens, dropouts, glitches, restarts, typical Windows problems.
After I switched to Apple and Logic everything changed immediately and I never looked back. Running smoothly from day one without having to tweeze BIOS and system settings like on Windows. Plug & Play! The Windows machine went to the recycling center!
And to make that clear: The Fireface 800 never had or caused any problems!
iMac M1, Fireface 800, Logic Pro X