While ordinary window glass absorbs a fair amount of uv radiation, enough gets through to be of concern. Many plastic resins are not uv stable, so the amount of exposure should be considered. Are you getting direct sun or indirect light? If only a little direct sun hits them during the day, I wouldn't worry too much. Too much sun exposure can also bleach wood veneers over a period of time also.
Will sun exposure damage my speakers?
I have a window next to one of my newly purchased JM Lab Electra 926s and since I like their look without the grill, I was wondering if I was hardening my cone surrounds or not. They are fiberglass "W" cones so I suppose they are ok but I don't know for sure. Has anyone looked into this before? Thanks! Arthur