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@jbamberg I wanted to confirm a setting for Mac OS X.
If I understand it correctly, the H9000 USB audio is clocked independently of the other digital audio. Is this true when synced over ADAT? I am currently clocking the H9000R via ADAT from an Apollo 8P while simultaneously using USB as an aggregate device. The setting I wanted to confirm is "Drift Correction". Should this be enabled even if the H9000 is clocked over ADAT?
The H9000 USB interface is clocked from the same source as everything else in the H9000, as determined by the "Clocksource" in the system settings. In your case, that's the ADAT input. So this means that the H9000 is clocking off the Apollo, so the H9000 USB audio should be in sync with the Apollo TB interface.
Refer to Apple's support article here: https://support.apple.com/guide/audio-midi-setup/set-aggregate-device-settings-ams094c7edb4/mac
This says that drift correction should be used when devices aren't hardware-synced to the same clock source. So, I don't think you'd need it in this case. You'd just need to set the Clock Source of the aggregate to be the Apollo (which it looks like it already is).