It looks like VB Audio’s ASIO Bridge does what I need.
It provides a WDM with up to 8 input channels (e.g. up to 7.1 to speakers) that it sends to the ASIO driver (Yamaha Steinberg USB ASIO). It also provides up to 2 output channels (e.g. stereo to recording program) from ASIO driver. You can set it to sample rates from 8K to 384K and bit depths from 8 to 24. It does not do rate conversion - you set it to match your audio interface and I believe Windows does conversion of any WASAPI inputs to the configured sample rate and bit depth.
ASIO Bridge is donationware - free if you want - $15 if you choose to donate (I have no relationship with VB audio other than using this product).
In my test, the UR824 and ASIO bridge were set to 96 kHz/24 bit and it worked fine with iTunes (44.1K/16 CD stereo), Spotify streaming (stereo), Youtube streaming (stereo), Sound cloud (streaming), Netflix app (5.1, streaming), and the Windows Speaker Test in Windows Control Program>Sound>“WDM Name”> Configure (set to 5.1 in my case).
For more info, see:
If you try to have ASIO Bridge and Pro Tools both use the ASIO interface at the same time, the first one gets in and the other does not. And if you happen to cause that conflict, you can back out of the conflict on either product without a reboot or without even having to restart either Pro Tools or the ASIO Bridge app. That is a really important thing and makes recovery mostly painless. The simplest rule is use VB Audio’s GUI to set ASIO OFF before starting Protools and then turn ASIO ON after closing Pro Tools.
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