One thing that does concern me is the fact all these sound cards are USB, and there is no way to "force" them to be assigned in any specific order.
Correct. The order that they appear is the order in which they're enumerated. Hmmmm... USB wasn't even SUPPORTED initially on NT V4 -- in fact, PnP and power management isn't supported on NT V4 -- so you must be using a third-party USB stack? I mean, heavens knows what information is available in that case!
It's even worse, by the way: Most of the USB sound cards (and certainly the 99 cent ones from China that I've tested) do not implement unique USB serial numbers. This is perfectly OK in terms of the USB spec, but it means that there's literally NO WAY to know which, specific, individual, USB device instance you're talking to. They all appear identical and interchangeable to the system.
Now, with a relatively large amount of effort, it IS possible to determine the port and hub a specific USB device is attached to. At least on the Microsoft-supplied USB stacks. But how would one provide this information in a usable way to the naive user of ScannerCast -- who just wants to plug their stuff in and get it working?
The whole multiple USB card thing is pretty much a mess, to be honest.
RE NT V4... NT V4 is a very good OS. It's AMAZING how fast it is and how little memory it runs in (compared to more recent generations of OS). If you can live with its limitations (old hardware support, no PnP/Power), it can be an exceptionally efficient platform, a lot like XP Embedded without the PnP/Power management.
Peter
K1PGV