if you ever get your hands on one, it takes a little getting used to at first. here's how i approach it.
starting with controls at noon, except master volumes if you need to be quieter.
i wouldn't go much past noon on the trebles or master presence control, because it tends to get harsh when overdone.
i set my master gain, which affects both channels, so that i can get very clean on the clean channel, and then i dial the bass controls on both channels to control warmth without too much boominess. my bogner cab had way more low end than my friend's ev 4x12 and the bass control was the key to making it work for both cabs.
then i start balancing the midrange knob against treble and bass. i turn the mid to 1-2 oclock on the clean channel to recreate a fat fendery clean. i love dropping a compressor in front of that channel for extra pop, smoothness, and carry on single notes.
the mid knob on the lead channel is very powerful and musical. test it by sweeping it off at first and then slowly rolling up to noon in small steps to hear what it does. fat, chirpy, singing...it's all in that bad boy! most other amps have mid controls that seem harmonically empty by comparison.
after playing the ds-100 i'm looking at what i can sell to get into another carol ann......shocked at how much i miss that tone!