Changing a speaker color

Depending on what color you like, I've sometimes considered using a vinyl wrap instead.  Removable. 

I would also recommend doing the vinyl wrap. Similar to what they do with vehicles.

It is very durable, has no problem being applied to a high gloss surface and can be removed if circumstances change.

Added bonus is that you can literally any surface treatment you can imagine. All you need is a digital file.

Never tried vinyl, but it sounds plausible.

In 1990, I took my raw MDF cabinets to a classic car painter. He sanded, filled, primed, sanded some more, and applied coats of black and clear lacquer. Aside from a few inevitable minor dings, the paint job looks unchanged in 30+ years, where they’ve resided in the living room of my large family. No cracks, peeling, wrinkles, crinkles, bubbles, runs, or other defects, and has even proven to be quite resilient to liquids.

wrap it in linex it seems to help to kill resonance even more.

I'm actually thinking about linex as well on my Aerial speakers 20+ years old vintage. Their look will definitely benefit and since it's not a vehicle not much disturbance the finish will face cuz it ain't a vehicle. 

I'm no painter so I would find a local auto body guy to do it for me.  I'd just remove the drivers, speaker terminals, etc. and drop them off.