Yamaha Steinberg ASIO Driver with UR242 + THR10

I recently bought a Yamaha THR10 amplifier and, more recently, a Steinberg UR242. I’m using Cubase Elements 10.

Using the Yamaha Steinberg USB ASIO driver, I can only select either the THR10 or the UR242, from the driver’s control panel, to use within Cubase. It is not possible to select both, to have access to the Ins and Outs within Studio Setup for both devices, at the same time.

Is this a fundamental limitation with the technology(ies) involved, preventing simultaneous use of more than one (both) USB devices within Cubase, or is it just a limitation of this particular ASIO driver? (in which case, could Yamaha/Steinberg fix that, if they wished?).

ASIO4ALL appears to be able to support multiple devices simultaneously, but I have found it to be unreliable doing so (at least within Cubase).

TIA.

ASIO only supports a single device (there are technical reasons for this).
ASIO4ALL bridges into the Windows drivers so you can see all of the windows devices but with subsequently higher latency.