Bridging Classe CA-100's

As a future upgrade I was considering picking up a second Classe CA-100(I can get one used usually for around 600 bucks)and bridging them.Has anyone tried this?I am not currently using a preamp,would I need one to do this?Any advice would be appreciated by this audiophile novice. Thank You- krelldog(I mean the dog who can't afford Krell)