As an part time interior designer I would suggest that you lose the red and go with a neutral color, something that picks up one of the colors from the stone around the fireplace, this will balance and pull together the whole room. Ultimately the speaker color is up to up but a nice gloss black will blend then into the entire picture, while I love the blue, great statement, it may not be everyones 'cup o tea' and does lend itself to being very catchy with regards to the eye.
Just an aside, attempt to get the TV up over the fireplace and centered in the opening you have, it would look great there.
Best of luck.
