When working with harmonics, you need to be delicate about the processing you apply. Any large EQ moves will ruin the totality of the sound. The best way of working with them can be using a tool like SigMod by Nugen Audio to split the signal into multiple chains to process individually.
Distortion is the alteration of the original shape (or other characteristics) of something. Audio distortion refers to any defamation of an output waveform compared to its input, such as:
Intermodulation Distortion (mixing phenomena)
Types of Saturation:
Even and Odd Harmonics
Full Saturation Harmonics
Clipping Harmonics = Square wave from clipping (overdriving the amperage capabilities of the circuit). Clipping harmonics can also look like Sawtooth waves from overdriving the speed capabilities of a circuit. This is why some people buy old gear, overdriving a signal through, to capture the natural distortion from these circuits.
Saturation = Even and odd harmonics
Clipping = Full spectrum saturation
Noise = Full spectrum frequency content
MV: This is what people when they say they “like the sound of clipping’. The addition of harmonics is better controlled with saturation and distortion plugins, rather than merely on the fader.