Can one really tell? I have often wondered about this. While I think actual failure of the woofer/driver/amp is immediately obvious -- what of the parts that slowly decay/degrade with time? I know caps can degrade, what else is in there that just slowly degrades with time? I guess the real question is. If I took a 10 year old 5000 and one that was brand new, would it sound the same? I don't know the answer.

Primary: MD600, MS200 (SpeakerLink to AES), Trinnov ST-2, Ayre V6-xe, Salk SS8 3x LRC.
Secondary: MC600 (whole house).
Zone one: 568.2, G57, MS200, Spatial Hologram M2SE.
Zone 2-6 (Awaiting assignment).