I just got a loaded Mark IIC+ and I am wanting to use the slave output with a Marshall head like Metallica did. Do I just plug a cable from the slave to the guitar input on the marshall head, or the FX return? Then does my guitar just plug into the Mesa, or the marshall? I am trying to duplicate the setup that Metallica used for Master of Puppets album. I still have plenty of other things to get (more mics etc), but I just need to know the basics before I invest in the marshall head. Any info anyone has on settings for this amp to get the Master of Puppets sound would be very helpful.