Yeah, Dean; it's more complex. Distortion in different components can add or subtract to/from each other depending on the phase relationships of the distortions. For example, negative amplifier feedback intentionally takes distortion sampled from the amplifier output, reverses it in polarity or phase, and adds it to the input("pre-distorting" it)so that the two distortions tend to cancel each other, making for a cleaner amplifier. In other situations these phase relationships are a matter of chance and can either increase or decrease the overall net distortion.
