1. sudo vi /etc/modprobe.d/blacklist-rgb-matrix.conf
2. add the following lines:

blacklist snd_bcm2835
blacklist snd_pcm
blacklist snd_timer
blacklist snd_pcsp
blacklist snd

3. Save the file and quit vi
4. sudo update-initramfs -u
5. reboot and confirm no "snd" modules are running by executing the command "lsmod"