mpv config

default.pa

#!/usr/bin/pulseaudio -nF
# This is: .config/pulse/default.pa

load-module module-alsa-card device_id="1" name="pci-0000_04_00.6" card_name="alsa_card.pci-0000_04_00.6" namereg_fail=false ignore_dB=no deferred_volume=yes use_ucm=yes avoid_resampling=no card_properties="module-udev-detect.discovered=1" tsched=no fixed_latency_range=yes fragments=32 fragment_size=128
set-sink-volume 0 32768

.include /etc/pulse/default.pa

# Default devices. `pacmd list-sinks` and `… list-sources` lists them.
.nofail
set-default-source alsa_input.pci-0000_04_00.6.analog-stereo
set-default-sink alsa_output.pci-0000_04_00.6.analog-stereo
.fail

mpv.conf

#.config/mpv/mpv.conf

# profile=gpu-hq
hwdec=vaapi-copy
hwdec-codecs=all
gpu-hwdec-interop=vaapi-egl
# upscaling
scale=spline36
# downscaling
dscale=mitchell

sub-auto=all
slang=SDH,eng,deu,ger,ces,cze,yid,zho,chi,lat
alang=deu,ger,eng,pol,ces,cze,yid,cho,zho,lat
# panscan=1.0

cache=yes
demuxer-max-bytes=123400KiB
demuxer-readahead-secs=5

audio-device=pulse/alsa_output.pci-0000_03_00.6.analog-stereo
#audio-device=alsa/front:CARD=Generic_1,DEV=0
volume=60

screenshot-format=webp

The mpv.conf is for hardware-decoded video.

Pulseaudio's default.pa for low-latency audio, which is needed for native games as well as Stadia. Without it you get the “trouty mouths” effect, i. e. puppets moving their mouth and a delayed audio.