"Next, you’ll want to carefully put the headphones on and — as you move the mic around — you’ll be able to hear the high and low frequencies change as you get phasing anomalies. Warning: Make sure the assistant engineer keeps the guitarist away, so he doesn’t plug in and blow your ears out! I usually end up placing the mic where it seems like I can hear the maximum high and low end responses. When you are finally ready to overdub the guitar parts, if it still doesn’t sound good, then to hell with it . . . forget everything I just told you, and place the mic where it looks cool!”
“I’ve got a technique I use when I overdub guitars. First, get a white noise tone generator (or just a loud hum from the guitar amp). Then send the microphone feed to the mixing desk and CRANK it through the headphones.