musical - 1. of or pertaining to music 2. having a pleasant sound, melodious, tuneful
One can argue that a sound is either musical, or not, that it isn't a matter of degree, but that's a poor argument due to the highly subjective assessment involved. In quite a few previous discussions of the way many enthusiasts use the term, it became apparent that a lot of folks hate the term and find it virtually, or even fully, useless. I sometimes use the term but have decided that detractors have a point. I tend to avoid it now, but old habits are hard to break so if I used it in my last (or next) post then feel free to bust me.
Someone who enjoys polytonal music with an unfamiliar scale... I might find their music quite 'unmusical' to my ear.
Using the word to make judgements about gear really just means pleasant. Pleasant, more pleasant and most pleasant? Sure, why not? But it doesn't really impart much of anything meaningful other than an opinion.
However, I do get the OP's point, and I also struggle with language when I encounter excellent sound from an outstandingly superior component. Trying such description makes me a little more willing to cut pro reviewers some slack when something they write seems silly, frivolous or snobbish.