Several years ago I drove a new ground rod directly outside of my dedicated listening room, and connected an 8 gauge ground wire to an isolated 20 amp receptacle. That receptacle feeds my Pure Power 2000 a/c regenerator and also my APC S20 power conditioner. That isolated ground was the only ground wire for my stereo system, and did not connect to my electrical panel. It worked fine but I did not notice any great improvement in my sound. Maybe I might have noticed a greater improvement if I had also ran the neutral wire to the new ground rod, or maybe not.
About a year later I was talking to one of my new club members who had moved to Florida from north of Dallas Texas, and is an electrician. Since he is an electrician I told him what I had done for an isolated ground in my system. This is freaky, but he told me that he had done the exact same thing in Texas. His ground rod was struck by lightning, and traveled through the ground wire into his isolated ground receptacle, and also caught his drapes on fire.
It had previously been in the back of my mind that the same thing could happen to me, because we get a tremendous amount of lightning where I live. My dedicated isolated ground receptacle is also behind my drapes, and I do not want to remove the drapes because they run the entire length of that wall. So I removed the eight gauge ground wire and reconnected the ground wire that goes to my electrical panel.
In the future I may try installing a plastic box on the exterior wall by the new ground rod and leaving enough wire inside the box to reconnect to the ground rod for brief usage at times when I’m sure there will not be lightning strikes. This is entirely illegal and shows that there are solid reasons for electrical codes, and most of all to always pull an electrical permit for new electrical work. If you do not want your house to burn down do not try the above.