In the terminal, type
sudo nano /etc/pulse/daemon.conf
Find the section that looks like this:
; default-sample-format = s16le
; default-sample-rate = 44100
and change it to this:
default-sample-format = s24le
default-sample-rate = 48000
(or default-sample-rate = 96000 or default-sample-rate = 192000 depending on what your system can support.)
Then save the file and in the terminal type
pulseaudio -k
Done.
EDIT: I should add, after making the change, you can see what pulseaudio is using with pacmd list-sinks | grep “sample spec” It'll show one result for each audio device.