All the control knob functions are described in their name and they act just like on a tube amp. High Gain and low Volume sounds darker, low Gain and high Volume will be brighter, but you have the Treble knob plus the Presence switch for fine tuning. That's all we want from a good drive pedal right? A balance. To smoothly overdrive a bright clean amp, or boosting some more sparkle in an already driven but dark amp. The Motive is very much a mids rich circuit by its nature, but with the Middle knob turned low, you can drastically scoop the mids. With every tone control at noon I was careful to balance the sound as transparent as possible, and from here you can tweak the tone stack knobs to your liking.
About the -\+ sign.
With Volume and Gain set to this position, the pedal should be clean and relatively at unity gain, considering the character difference between the two channels. One more trick I could do here thanks to the parallel gain, is that turning down the gain the sound will not go to zero. With the Gain in the -\ zone the Motive will simulate the character of a smaller amp instead of cutting out totally. For this "amp shrinking" effect, start experimenting with all the tone controls and the Volume at maximum and Gain at minimum, Channel on Boost and Presence on Smooth. As you turn up the gain, the amp is getting bigger. Now you can dial out what you don't need.
Besides the Normal, two more options to balance the overall treble content of your sound with the character of the amp and the pedals is used with. Glass is boosting treble content for the dark sounding amps, and Smooth can be used with a bright sounding amp to avoid shrill sound when boosted or overdriven with the Motive. Fine tune it with the Treble knob.
It is rebiassing the second amplification stage with two more options that I like. The Bright is more cutting through, good match for humbuckers, and the Boost is just right for fattening up single coils. Hint. When playing with higher gain and looking for a good rock tone, give the Boost to the Raw to go totally train wrecking or Smooth out the Bright and you have sold an overdrive crunch.
With all the knobs at noon, Channel on Warm and Presence on Normal, JAZZ (Blue) is the tight bass, high headroom sound for the seekers of the holy grail D amp tone. With the same settings, the ROCK (Red) is a more even and slightly more powerful sound, with more body and sparkle that breaks up quicker. Switching between the two, can also take place of the boosting or taming function of a dual channel amp that shares the same tonestack.