Its hard to comment without relating things I'm not sure about.
From rewriting the INF it looks like they were confused, or Microsoft switched the default multimedia class devices underneath in DirectX for the Audio and Video crossbar.. originally it looks like they used the same one.. later Microsoft definitely introduced a specialized one for Audio versus Video.
I am an amateur at this and DirectX technology.. so I'm very unsure of what I am looking at.
Comparing it to the empia2860 INF which does very similar things flawlessly on Vista, Win7 and Win10 it "appears" this can be sorted out.. no guarantees though.
If it works with the ATI USB 2.0n it is (possible) similar fixes might work with the PCI models as well.
I was deep diving in old MSDN archives last night and (saw) that Win10 x32 does not enforce driver signing.. so another reason to use 32 bit versions of windows.. no vendor lock-out for old hardware !
closer I get.. more demands on my personal time.. so i may be taking a break here..
i (did) finish rewriting the INF file for ATI USB2.0n but have not tested it
its not reverse engineering or code rewriting.. its just rewriting the instructions to the operating system on how to use what's there.. the drivers themselves "could be" fundamentally be broken.. but time will tell