Audio issues - Audio randomly stops working (usually while using Firefox)

You should consider updating system BIOS
ASRock > X99 Extreme3

Kernel v5.12.19 is no longer supported on Manjaro
I suggest you replace this kernel with kernel v5.14

I also suggest you turn off the Auto-Mute setting in ALSA
This is a useful feature for laptop systems so that internal speakers are muted when headphones are plugged in, but users with desktop systems may not want the rear audio jack sockets muted when headphones are

amixer --card=0 sset 'Auto-Mute Mode' disabled

(replacing PulseAudio with PipeWire would not resolve an issue in ALSA)

Specifications for USB Speakers state
https://audioengineusa.com/product_tech_specs/hd3-wireless-speakers/

  • USB 1.1 class-compliant
  • supports a Bit Depth of 24 bits
  • supports Sample Rates of 44.1 kHz and 48 kHz

PulseAudio default bit depth is 16 bits, so USB device should work better if this is reconfigured to 24 bits
Use this command to check PulseAudio configuration

pulseaudio --dump-conf | grep sample