Raspberry pi 1 model b sound

Volumio installed on Raspberry pi 1 model B. Want to get best sound possible of it so…have output going to HDMI with intention of connecting HDMI to coax adapter that allows me to connect to coax port on my integrated amp.

Question. How would you expect to this setup to sound ? No longer available but if I had a Hifiberry hat with coax (coax) output would that sound better?

Trying to understand if the model b setup above would provide just as good sound as say a Raspberry 3 setup with soundcard that i plug via coax nto my amp. Basically if if I upgrade will I get a difference in sound quality.