U3421WE, hissing with 16bit; 24bit only temp. selectable

Hi,

I have a Dell U3421WE connected to a Lenovo P1 laptop (Nvidia Quadro P2000 with Max-Q Design) via USB-C.

The system is running Windows 10H2 and the Nvidia driver is 27.21.14.6192 / 1.3.38.40.

I noticed a strong hissing when playing some sound via the monitor. Searching a while in the web I found that this is caused by the 16bit audio setting of the monitor audio device and one should change it to 24bit.

However, if I go to audio options > audio control panel > Dell U3421WE > Supported Formats, only 16bit is offered.

If I disable and re-enable the "Nvidia Quadro P2000 with Max-Q Design" from the device manager out of a sudden the Dell monitor is reported being capable of 16bit and 24bit.

I can now change the default sound settings in the advanced tab to 24bit 48khz and get a decent sound out of the monitor.

However, after reboot of the machine, the monitor's supported formats are back to 16bit only unless I disable and re-enable the graphics card again.

This is really annoying. How can I solve the issue?