modinfo snd-hda-intel confirms parameter power_save is available for snd_hda_intel driver, but would have no effect on USB devices using a different driver
modinfo snd-usb-audio does not show parameter power_save available for snd_usb_audio driver
Modprobe option for snd-usb-audio is probably not recognised and ignored
One workaround to prevent USB device being suspended is to leave PulseAudio Volume Control pavucontrol open on desktop
(pavucontrol works with PulseAudio and pipewire-pulse )
If you were using PulseAudio and pavucontrol works to allow playback without a fade-in, module suspend-on-idle can be disabled for a permanent solution
AFAIK PipeWire does not have a similar module and device suspend is managed by pipewire-media-session or wireplumber