I'm most of curious how you force your DAC to run at a fixed sample rate.
Most of the time this is done using the settings in the Win Audio panel.
The moment you use an exclusive mode (bypassing the win audio stack), you get automatic sample rate switching.
However, some ASIO interfaces might allow you to set a fixed sample rate.
Maybe the answer is in a recent post. by sveakul
If you are playing files with wasapi-exclusive that have sampling rates incompatible with your audio device, bass.dll will re-sample on the fly to a compatible rate.
Might apply to ASIO as well.