Can speakers be tested?

I think my Magneplars have been damaged by UV light. I had strong sun coming through large windows and passing across the speakers for at least two summers.

They weren't connected at the time but I recently hooked them up and they suck!

Can they be tested to see how much they vary from spec?

Thanks - rev
I know I'll probably make a lot of people mad by saying this but that’s just the way Magneplars sound. More likely than not, you just got used to listening to other speakers.
UV and humidity are known to cause delamination in older models. I think having strong UV pass though a mylar polymer is a really bad idea. Since they haven't been used in a very long time, its worth letting them play for 20 hours or so before you make a judgement, but I think it is not unlikely that degredation of the mylar and or glue that holds the wires to the mylar has been damaged.
Of course.Take them to a local speaker tech and he will pass a number of sonic tones at various frequencies to see if they are performing up to spec.This will take just a few minutes and you will have your answer.
Sunlight(UV) does not degrade Mylar, BUT will deteriorate the glue, holding the wires to the older models. Magnepan mentioned that fact in their User Manuals, and cautioned against placing them in sunlight. If that(glue failure) is the case with your speakers; you'll hear them noticeably rattling during play. If not(as mentioned by the first respondent); yout ears have probably just acclimated to the sound of your other speakers.
Uh Oh ZD542...Did you hear that car door slam??? It's Elizabeth, I would start running if I were you. :o)