Why does the RAT distortion pedal sound better?
Because it was carefully designed to produce “musical” distortion. Most conventional distortion pedals clip the signal in a totally haphazard way, producing a lot of extremely “brittle” sounding high-order odd harmonics that result in that tinny “fuzztone buzz”. The RAT pedal has specially contoured EQ circuitry that alters the frequency response as the distortion is increased to simulate the smooth sustain of an overdriven tube amp like a Marshall or a Fender Twin. This “sweet” but raunchy sound is what we refer to as “musical” distortion, because it enriches the signal in a musically desirable way.