Did the shop recommend the arrows based upon what the sticker on the limbs said or did they take into account that you are shooting almost 80#?
I'm not familiar with those arrows, but the designation tells me, probably pretty light, and/or underspined.

The Rage if memory serves me isn't exactly the quietest bow to begin with, so a heavier arrow will be a big plus in quieting down a 76# bow. If you shot your current arrow, next to a 500gr one you'd immediately feel and hear the difference.
The cheapy stabilizer is no help either.......lots of good technology on the market to help there.
Check your tune, and SIMS it up, anywhere you can jam some rubber won't hurt.