What does 'Fast mean?

Fast usually means the sound is thin and without body/weight making it seem faster! That is what I have found when auditioning "fast" gear.

Bill

Like my amp, my typing skills are fast but unlike my amp, I am not accurate. Rwwear, I agree more is better than less. Bbaxely2, it is understandable your girlfriend would prefer a slower hand, good sense of humor!

In all seriousness an amp with several small caps can recharge themselves more quickly than say only two or four much larger caps. Like the McCormack amps using several small caps with each one located close to each individual output device equals a fast amp. This can be heard but difficult to descibe. Cannot speak for cabling and its contribution to this phenominum, I never changed cable to prove this theory only to improve & get the desired sound quality.

Glidewriter, is right when he says, "Truly fast gear will track complex waveforms precisely, neither lagging behind rising edges or overshooting trailing edges."

As an example, Class D amps are fast. They don't waste nearly as much energy during their switching chores, so can more adroitly cover complex passages. If you have a fast transducer, you are in for a treat.

fast means no smearing of the sound.