Adding second "dedicated" breaker box.

I think you will be better off running the dedicated line off the main panel. But if you are running out of room and need a sub-panel, make sure the ground of the sub-panel is connected back to the main panel. Never connect the ground from the sub-panel to a separate ground rod otherwise, it will be a safety code violation and may introduce unsolvable ground loop problem.

I thought the sub-panel was suppose to have it's own separate ground rod a few feet away from the ground rod for the main panel. The main ground rod and sub-panel ground should be attached with the same gauge copper wire as used from the main panel to ground rod and clamped. Is that against code and present any dangers? Would it make any improvement is sound quality?
Thanks in advance...

Lak,
I am talking about safety issue, not sound quality. Some people claim that separate ground rod(s) results better sound. I cannot dispute that because I have not tried that due to safety concerns.

Sidssp,
I'm wondering what the safety concerns are? Maybe I need to rethink the way I grounded my sub-panel as described above?

Lak - you should definitely rethink your grounding scheme. It's illegal and potentially dangerous.