Success!!!
Turned out to be a mismatch in nodejs versions. I had a later version 10.15.2~dfsg-2+rpi1 installed than what the service was expecting 9.11.2-1nodesource1.
From the daemon.log file:
Uninstalled new nodejs version:
sudo apt-get purge nodejs
Installed old nodejs version:
sudo apt-get install nodejs=9.11.2-1nodesource1
Rebooted:
sudo reboot
I am now able to successfully cast to Plexamp on my Raspberry Pi 
I’m not sure if this is the right place to ask but will Plexamp always have this dependency on node version 9?
Thanks again @waltonbruce01 for pointing me in the right direction, it is much appreciated
Can finally whip the bllama’s ass 
Good Times!
