Hi guys, sorry for the late reply.
Tzh2ly: The terms faster and slow refer to the attack of a note e.g. the key of a piano or the strings of a guitar or harps, and not to the tempo(speed) of the music (i.e. bits per minute). Of course, a whole orchestra consisting of 30 or more people can not be very fast. Regarding the term color, in the hi-fi jargon this term is used to express deviation form neutrality. This is what I have also meant. Of course having some color (i.e. deviation from neutrality) is often a good thing (nobody wants to listen music in an anechoic room for example).
Audiozen: Regarding the slew rate of an amplifier, by looking at its definition, i.e. the maximum value of the time derivative of the voltage, I would say that the slew rate of an amp is equivalent to the acceleration and not to the RPMs of a car. One can always make analogies between mechanical and electrical quantities. By doing so one can find that charge plays in electricity the same role length plays in mechanics. Thus, using Ohm's law (for a given constant resistor) and the fact that electrical current is the time derivative of charge one obtains that the slew rate is proportional to the second derivative of charge with respect to time. Since charge is equivalent to length, and the acceleration is the second derivatives of length with respect to time it should be clear that the slew rate should be associated to acceleration and not to RPMs (after all RPMs is just a number it have no units).
Best wishes,
Paul