This is a fun & Common occurrence these days. I've been doing it for years. You always want a live guitar amplifier for the guitarist. Especially if feedback affects from high gain conditions are a part of the sound. You use a high impedance active FET DI box to also record the guitar directly. After recording, you can simply take the output of the multitrack machine and patch that into another guitar amplifier of your choice. Now because of the level difference, you may have to include an external pad so as not to overload the guitar amplifier input from a high output line level source. Your guitar puts out much lower level. You may also have ground loop issues that can cause serious hum & buzz. The only way to eliminate that is by lifting grounds BUT BEWARE! YOU COULD CAUSE A DEADLY SHORT. You wouldn't be the first to be killed this way. The benefits can outweigh the risks by checking grounds between pieces of equipment with an AC volt meter. That being said, you can then put microphones on that amplifier and record that to an additional track. Put one microphone close & one on the other side of the room and record 2 extra tracks. Swap out a different amplifier, lather, rinse, repeat for the most beautiful full-bodied guitar hairball. Don't forget to add some time delay & call me in the morning.

Doctor Director
Ms. Remy Ann David

Ok I understand the potential ground loop problems and I know how to deal with them safely, but the external pad has me a little baffled. I understand what a pad switch does, it lowers the input/ output ratio (I think) but what device would I need to use?

i am new at this, but I just got a reamp device:

http://www.reamp.com

it allows you to run back through to any amp you want. So far so good - gives me control of the sound after the guitarist leaves the studio. For me it's great because I'm not pro - so I can spend hours trying to get the mic's right and testing the sound without tying up the muscians.