[A27Hull]

Thanks Mike. The ground switch is there, and the plug is 2 prong. The consequence to switching to 3 prong is the elimination of the ground lift switch then?

What would opening the neutral wire do in the 3 prong scheme? Put the 120 across that open? If the neutral wire is already connected to the chassis, would I need to find it and disconnect it also to implement the 3 prong scheme?

I ask because we've been fond of using the ground switch to eliminate/reduce hum with guitars.

I'm sure my ignorance is showing on this one, but I'm kinda playing on-site studio tech.

I've read that in three prong modern systems, the neutral wire is connected to earth back at the main breaker terminal, so I guess that a neutral short to chassis, the neutral being shorted to earth ground at the main breaker, would create a ground loop between the neutral/chassis and ground, and possibly in the operator touching the chassis and standing on earth ground.