TUBE AMP SATURATION USING A BOOST
This is the oldest tone trick in the book. Tube amps sound best when they're being pushed. Using a gain pedal in front of an amp results in additional breakup and compression. This works best with smaller tube amps, as they run out of headroom quicker, and trip into power tube saturation. For higher-wattage amps, add some preamp gain at the amp, too.
DON'T USE TOO MUCH GAIN
Most of the time, distortion and overdrive pedals don't sound great when maxed out. Start at a low setting, and gradually raise the gain until you're happy with the sound. Even for metal, most bands are using less gain than you think. As discussed above, into a tube amp, the level control is the one you want to push as high as possible to thicken your sound.
