It would be really fun and make music stack exchange even more unique if the upvote icon on a post could be a half-rest, and the downvote icon could be a whole-rest.
Not happening. From a Stack Exchange product manager:
things like voting and favorite buttons are a core part of the Q&A experience that should be shared across the network. It was a mistake that we ever allowed for those to be themed.
While we did have some lovely customisation, Stack Exchange worked out it took far too much effort to manage all of the various customisations and have taken the official line of consolidating to one set of icons etc across every site, with an associated responsive UI.
So no, we will definitely not be getting customised icons back again. Sorry.
While I think it's a clever idea, I haven't seen any other SE site do this; it seems to me like something you'd see on Reddit, but not on SE.
This doesn't mean that SE doesn't allow it; maybe they do, and I just don't know it. But Who decides the layout and icons of a site? Are they open to vote? suggests that it might not be something we could get running.
This might be another question best suited for Meta.SE, but if you ask there, make sure to make it more general: "can we request specific voting icons," not "can Music.SE request specific voting icons." Perhaps such a question already exists, but I can't find it.