Amp "timing" ?

^^ +1

There are things that might be considered timing issues in amps, but when used in the context of a review is probably referring to detail and has nothing to do with timing at all. There is this term- PRAT which is thought to be a British thing, which refers to Pace Rhythm And Timing.
But it should be quite obvious that an amplifier can't change the timing of music; IMO this has more to do with the amplifier being low enough of the bad kinds of distortion to which the ear is keenly sensitive so that the music is processed in the limbic centers of the brain rather than the cerebral cortex. There is a tipping point for this where if the unconscious brain sorts out that there is something wrong with the 'music' it transfers the music processing from one to the other. When this happens the emotional response to the music is lost or attenuated- less toe tapping...