AMT8 in Catalina

[Jay Vaughan]

> Good point about USB power supply. I think I tried them on a powered hub at the time and the problems were extremely deterministic, so I doubt that was the root cause for the MIDI interfaces. It also occasionally choked on streams of MIDI clock messages with the Cirklon that has its own power supply, so I rather expect a timing / buffering issue. 

Yeah, just to expand on this a bit, because its been the bane of my existence for years now, professionally ..  some USB hardware micro controllers (especially those based on an 8051 core with USB MAC)  go into a psychotic state of reset loops if they don’t get quite the amps they expect, and this triggers all kinds of driver shenanigans, especially on Windows where multi-stage shim driver/enumeration is a more frequently adopted technique by driver writers - and Windows has protection modes on a lot of these drivers where it will internally blacklist/timeout a module if it freaks out too much, to prevent BSOD conditions.

When in doubt, always use an external high quality powered USB hub, even if you are confident your motherboard is high class. USB has multiple fail modes.

j.