Now before you go and switch off the default treble setting, I implore you to give it a shot first as there is some method to the madness that is a treble booster. When the treble frequencies are boosted into an already cranked and compressing amplifier, something special and perhaps unexpected happens. The treble compresses even more, making it creamy smooth, while the rest of the frequencies get a boost as well bringing them up closer to the treble volume in the mix. The final results being a creamy over-driven amp that is perceived to have less treble. Go figure.
If you amp isn’t to the point of compression (hello Silverface Twin Reverb), then switch the tone to either the mid or low settings (based on your guitar) and you get a huge range of volume boost with some of that almost fuzz like compression and gain boost. Alternative run this pedal into the front of another low-medium gain pedal and hold on to the smooth, thick almost fuzzy goodness.
A final note, this pedal is germanium based and as such does best when your guitar is the only thing in front of it. Crank it up and you get that beautiful volume sensitivity that lets you turn down the gain from your guitar without affecting the overall volume of the signal much. Of course, there are no rules, so try it out anywhere in your rig that you want; throw it behind your other pedals as a final volume boost with some thickness and it will still do just fine.