Since version 6.5.1, the stream sample resolution is passed through to audio I/O core.
On Mac OS it works fine. But with Windows 7 and Thesycon (2.23) driver I get only the sample resolution of the STREAM_FORMAT_OUTPUT_1, regardless of the selected bit rate. (Tested with Windows control panel Sound and Foobar).
Is this a restriction of Windows?
Stream sample resolution USB Audio
In the control panel of the Thesycon evaluation driver you should see multiple output formats listed.