Doing as you described is what a lot of people do, but the two channels are coupled together anyway. If you plug into the "normal" channel and turn up the "bright" knob, you get a little more of the edge to the sound. Get the volume you need from the normal volume control and add some crunch with the bright knob. It gives you flexibility to get a more overdriven sound at lower volumes. Running a cord to the channel also does this, but then the travel on the bright knob is just as limited as the normal volume knob (i.e. you go much past three and you've got feedback.) Try it both ways and see.
Bernie Clarke "Don't start me to talkin'. I'll tell everything I know." - SBWII