If all your equipment is now plugged into one ungrounded outlet and there is not any grounded objects with in arms length of the audio system, imo, it is safer that way than it would be if you installed a dedicated separate ground wire to an isolated outside earth ground rod.
What you should do is hire an electrician to install at least a couple of new dedicated branch circuits.
NEC does allows a 2 wire receptacle to be replaced with a GFI receptacle. A GFI receptacle will still operate as designed if an equipment ground is not present. NEC does require the receptacle cover plate to have a label stating "No Equipment Ground". The cover plate also needs to be plastic or nylon, no metal plate....
What you should do is hire an electrician to install at least a couple of new dedicated branch circuits.
NEC does allows a 2 wire receptacle to be replaced with a GFI receptacle. A GFI receptacle will still operate as designed if an equipment ground is not present. NEC does require the receptacle cover plate to have a label stating "No Equipment Ground". The cover plate also needs to be plastic or nylon, no metal plate....