Amazon FIRE STICK - older version non power on -off button volume settings

[suzonka]

I found out on my fire stick by turning off HDMI PLUS+ I gained about 20% more sound volume to my TV's optical out however I need more volume out of my optical out port to get this greater volume from the fire stick what would be a way to gain more volume ? - I have also tried Blue tooth paired to my sound bar from my fire stick blue tooth and it gets very high 90% volume however its very distorted ,not good.