@douglas_schroeder
Your dedicated circuits to your audio room could be protected by a individual 20 amp breaker with its own surge suppression built in most manufactures sell them Square D, Siemens, etc. I would also have the electrician test your grounding electrode system and make sure your reading from ground to earth is 25 ohms or less to ensure its integrity is up to the task of dissipating faults even small ones in the system. Also if you keep your sub panel and just change the main have your electrician make sure the downstream sub is properly wired// grounds and neutrals are separated and only bonded together at the source. You would want current flowing on the grounds.
Your dedicated circuits to your audio room could be protected by a individual 20 amp breaker with its own surge suppression built in most manufactures sell them Square D, Siemens, etc. I would also have the electrician test your grounding electrode system and make sure your reading from ground to earth is 25 ohms or less to ensure its integrity is up to the task of dissipating faults even small ones in the system. Also if you keep your sub panel and just change the main have your electrician make sure the downstream sub is properly wired// grounds and neutrals are separated and only bonded together at the source. You would want current flowing on the grounds.