I was thinking of my response and then read what Guido wrote and realized I would say the same thing. Al articulated further and I agree with what he added and with his summary that warmth is frequency related.
The lower midrange emphasis is most commonly associated with warmth but it can also come with slightly suppressed high frequencies and bass that is either, or both, rolled off at the very low end and perhaps a bit "fat" or somewhat less than detailed/defined. IMO a rich sound is all about tone and harmonic structure and is always a good thing. I also find the terms "dark" and "bright" interesting but different in that I would characterize them as describing a frequency shift either lower (dark) or higher (bright) that can be independent, or in conjunction with, being warm or rich.
All of these are preferences and Guido makes a good point that a system can sound both neutral and rich, which I find a very good combination, but would add just a touch of warmth and darkness to achieve the sound I enjoy.
The lower midrange emphasis is most commonly associated with warmth but it can also come with slightly suppressed high frequencies and bass that is either, or both, rolled off at the very low end and perhaps a bit "fat" or somewhat less than detailed/defined. IMO a rich sound is all about tone and harmonic structure and is always a good thing. I also find the terms "dark" and "bright" interesting but different in that I would characterize them as describing a frequency shift either lower (dark) or higher (bright) that can be independent, or in conjunction with, being warm or rich.
All of these are preferences and Guido makes a good point that a system can sound both neutral and rich, which I find a very good combination, but would add just a touch of warmth and darkness to achieve the sound I enjoy.