Originally Posted by Mike Halloran
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didn't realize that USB is backward compatible.

That's because it's not for the reasons that I already explained.

Glad you got it working.
Backward compatible, in this instance, simply means that if you plug a USB2 device into a USB3 socket you can usually expect it to work, as indeed it is doing in the OPs diagram. It's just not necessary to complicate things by delving into protocols. Similarly, Class Compliant just means that the device does not need a bespoke driver to work, as is the case with most synths and controlling keyboards. Let's keep it simple. All I was trying to do was help Bass Thumper solve his problem, as I'm sure rharv was too, and I'm pleased we've sorted it.