The first step towards PERFECTION is to listen to your speakers and then write down a list of all the things which are imperfect about them. Do it Dill and then come back
^That^ is not a bad exercise…
However the grill or box colour, the material and the shape of the speaker are more things that I would suspect an interior decorator, or Feng Shui master, would care about.
They do not, by definition, affect the sound.