I had hung on to the receipt for many years, which was good, cause in my younger days I really cranked it up, and the lifetime warranty helped out with woofer replacements!
The receipt is long gone, but that's OK, since I just listen at low volume to Lawrence Welk and Mantovani (do I really need the sarcasm tag?). LOL
Our speakers are about 16-17 years old too. We’ve had to replace our sub-woofer, but other than that, our surround sound system is original. They’re all B&Ws.
Never should have thrown mine away. They cost me a fortune back then and they would be worth at least as much today. Ah well, live and learn.