What no-one has mentioned is the amplifier's damping factor, i.e. the amps ability to control the loudspeaker motion and produce cleaner and clearer tone at all frequencies.
There is a good explanation at [url="http://www.crownaudio.com/pdf/amps/damping_factor.pdf"]http://www.crownaudio.com/pdf/amps/damping_factor.pdf[/url]
Cable resistance has a significant effect on this. Typically 1.5-sq.mm. cable has 3 times the resistance of 4-sq.mm., 2.5-sqmm. is almost double.