Isolated Ground causes ground hum.

I would think long and hard about adding the ground rods.  If you did get hit by lightning or gave an electrical fire, it’s a sure bet your homeowners insurance may be quite reluctant to cover the loss.  To be sure, I would have a local certified and licensed electrician check out your wiring set up. 

@JEA48

As far as I know, the NEC does not specificity a maximum number of ground rods, so long as they are all bonded together. That's what I am referring to.

Best,
E

@ erik_squires

Thank you for the clarification.

Yes you are correct there is no limit to the number of earth ground rods as long as they are all tied together. They then become one electrode. One ground wire is extended and then connected to the service entrance neutral conductor in the main electrical service equipment/panel.
Jim

Check out the Ground Master box from Puritan Audio. It will cost you $165 you will just need to connect your ground wire to it. You can read Paul Rikby’s review.

Please don’t add any ground rods yourself. 
Have a licensed sparky do it. I’m sure it won’t improve your current sq situation.