Multichannel Digital Audio Issue For Quadro Cards

Go to the following link (https://nvidia.custhelp.com/app/answers/detail/a_id/2796/~/which-hdmi-audio-formats-do-nvidia-gpus-support%3F) and you will find what digital audio output is supported by GeForce cards. There is a notable typo where it references the 900 series, calling it Kepler. I assume they mean Maxwell. Note that the 900 series of GeForce cards is said here to support up to 24 bit/192khz digital output.

I have an Nvidia Quadro M4000 for video rendering and editing. It is currently the only video card in my system and I need it to be able to output at least 24 bit/48 khz digital audio to a receiver so that I can do some multichannel sound mixing at a decent quality, but I’ve tried connecting multiple HDMI devices to the GPU and I am only allowed to output 16 bit/48 khz audio on all of these devices. I assume that since the M4000 is Maxwell-based, it should be able to support the same audio output as a GeForce 980 at least on a hardware level. Is this a driver oversight? Has anyone else had issues with digital audio output on Quadro graphics cards?

I’ve sent messages to NVidia support about this to no avail. Despite their “response in 24 hours” automatic emails, they’ve been completely silent.