In a nutshell, guitar re-amping involves routing an already recorded track to an amplifier, and “re-recording” the amplified sound. Noted producer and engineer John Cuniberti (Joe Satriani, G3, Jerry Garcia Band) built the first dedicated hardware re-amping device—the Reamp—in 1994. Today, of course, various DAW plug-ins can also take a direct guitar track and transform the “amped” sound instantly.
“A pre-recorded guitar track can be re-amplified to either reinforce or replace the original track,” explains Cuniberti. “And we now see guitar players thinking ahead, and recording a direct track along with their normal amp setup, which allows them to later change the sound of the amp or amps without re-performing the part. Most professional direct boxes have an unbalanced 1/4" output that can feed a guitar amp without adversely affecting the sound, and there are also standalone splitters available. And because the Reamp converts the signal to that of a guitar pickup and unbalances the line, both guitar amps and stompboxes act as if a guitar is plugged into them, which also lets you use stompboxes as ‘outboard effects’ at any time—including during mixing.”
Visit reamp.com for detailed information on re-amping