McIntosh XRT25 Question

Whatever you do, keep the drivers out of the sun.  UV light is their worst enemy and will breakdown, usually, the foam or elastic surround first.  I have several speakers that are 40+ years old.  I have 2 pairs of Altec Lansing A7 500's that sound wonderful.  The older pair to me is actually newer at about 40+ years old and the newer pair to me was purchased by the first owner in 1958.  The older pair is actually new old stock and was never assembled.  The newer pair has seen a fair amount of use.  In both cases the driver and horn assembly works perfectly.  On the new pair, that has seen lots of use, I believe it could use a new crossover.  Still sounds great but not as defined as the older pair.  Your ears are the ultimate jury and judge.  Another thing you can do, is to drop out the woofer and see if you can get sight of the crossover.  These will have capacitors in them.  Look for bulges on the end.  This is a sign they are about to go.  I also have a friend with a old pair of JBL L-150's that had his speakers re-magnetized.  He said they got faster than what they were before.  Good luck.