Sometimes it could be the other way around: polite sound could be the result of a significant amount of dynamic headroom (amplifier) and lack of distortion. The sound becomes very clean and due to the dynamic headroom one feels never "stressed" when listening. In real life music never sounds stressed or "dynamic". It sounds very "relaxed" with plenty dynamics, but never forced. Sometimes I think when I'm attending a live classical music concert (orchestra): it's kinda dull and polite sounding, but of course it isn't. It's a psychoacoustical thing. Like amplifiers with little dynamic headroom that can sound very "dynamic" and up front (which is a bit contradictory, I know) .
Chris
Chris