But seriously, most of these audiophile sayings are just gibberish from people who don't understand what they are talking about.
Music might be a complex waveform, but that doesn't mean that it doesn't adhere to the same laws of nature as everything else, that there is any sort of magic to it, if you will.
That it a topic that has been discussed quite a bit in this forum, the unclear/incorrect vocabulary in so many audio enthusiast forums and other publications.
What would "play faster musical parts better" mean to you?
What I can say from the published specs for both the Zen Can and the Atom is that, at normal listening levels (<1Vrms), the Atom will have higher SINAD. If that goes to an extent where it does make an audible difference? I don't know. If Amir tests the Zen Can we would be wiser for it.
The Atom seems to have a lower noise floor, wich could/would make an actual audible difference with highly sensitive headphones like IEMs.
With less sensitive mainstream over ear headphones like AKG K700s, Beyer DT7/8/900 and anything similar, there would very likely not be audible differences, an amp would have to be a complete failure (by the standards of this forum) to be distinguishable at that output level.
Furthermore: sighted, non-level-matched testing doesn't help you on forming an honest opinion about the sound (or lack thereof) of a component, it will only reaffirm your (subconscious) biases. Everybody falls victim to that, I know I have many times.