Okay, I'm an idiot when it comes to electronics stuff, but (and?) I don't understand why you'd need a pull-down resistor here. If you've just got a SPST switch between the mute and 12v lines, there should be no difference between when it's open and if it were just unconnected altogether, which is how I imagine most empeg installs are, including mine, and I don't get random things happening to me.