There will be as many digital audio devices as there are hdmi/display ports.
24bit 48000Hz is the max my laptop supports as my laptop audio hardware is weaker,anyway you need to use really expensive audio equipment to fully utilize 32bit audio.Try 24bit 48000Hz to see if it improves your audio.Just a guess but maybe setting audio quality output too high with speakers like these maybe the reason for this audio issue.
24bit 48000Hz is the max my laptop supports as my laptop audio hardware is weaker,anyway you need to use really expensive audio equipment to fully utilize 32bit audio.Try 24bit 48000Hz to see if it improves your audio.Just a guess but maybe setting audio quality output too high with speakers like these maybe the reason for this audio issue.