I've had one for years... they're absolutely brilliant!! On mine there is a "summing mod" [factory] where I can use the pre's as individual mic amps or combine the two signals with a master out.
I will often use this for close and distant mics on guitars or if I use two mics on a snare drum [the TG-2 will sound AMAZING on both sounds... as well as many other sounds... bass, vocals, you name it].