Musical (or musicality) - A sense of cohesion and subjective "rightness" in the sound - From Describing Sound A Glossary
I think the thing called musicality is widely used in describing sound but actually it's very very subjective. From my observation so far, people tend to describe a headphone musical when it is easy to listen to because of the good midrange ( thick, lush,...) and non-fatiguing presentation as well as several more things. Moreover, as the definition above stated, it is not the same for everyone because everyone has his/her own standard of how the sound is right or wrong ;)
Thanks for responding. I too see that word as very subjective, so much so that I think it fails in its usefulness as a word. It doesn't really convey information. I usually assume people mean "more bass" but who knows. It would be much more simple and clear to say "more bass."