I have been looking for a while on the forum for some precise indications about the best way to use the Clean and Distortion Sense, and I have yet to find a definitive technical explanation about them. However, I can share the way I use them, and a way to understand what they do. Here is a three minutes experimentation that you can do.
1/ Choose a Rig which has a default Gain of about 8 (7 or 8 leds on the 15 total). Get accustomed to its sound.
2/ Push/Hold [INPUT]. Now you have access to the Clean Sense / Distortion Sense settings.
3/ Set the {GAIN} to 0. You get now the clean sound of the amplifier. It is clean, and the output volume may become very low.
4/ While hitting strings on the guitar, move the {Clean Sense} slowly from 0.0 to 10.0 and back, a few times. Note how effectively this changes the volume. This helps you select the volume setting that you like in "clean" mode, as this becomes the volume that you get when Gain is to its minimum.
5/ You can tweak the {Distortion Sense}, and notice it has no effect on the sound, or the volume of the sound.
6/ Set back the {GAIN} to its defaut ( 8 ) value.
7/ Move the {Clean Sense} slowly, still hitting guitar strings. Note that this has no, or almost no action on the sound or its volume.
8/ Move the {Distortion Sense} from -5.0 to 5.0, still hitting the strings. Note how effectively the distorded sound changes between these values. Low values make it cleaner, high values make it more distorded.
9/ You can select here the most appropriate value for your guitar : typically under 0.0 for very hot pick-ups, much over 0 for low output PU.
10/ Note also that Clean and Distortion sense have almost no effect when Gain is pushed to its maximum.
11/ The experimentation is over : push [EXIT].
I found that this has helped me much understanding the usage of these knobs.
Please react if i'm wrong, if I missed something, or if the explanations are not clean enough.
Best Regards.
Jean-Jacques.