The longest you have owned any gear?

My aiwa ad f770 cassette deck, since 1983 to present. It still works as good as day one, with a new set of  belts. Second I guess would be 2 of the many tuners I own. The marantz st6000 and the cambridge t500.

I still have my Acoustics Research Amplifier, bought new in 1969 (50 years?!).  In active use until it was peacefully retired into storage in 2012.

My Ariston RD11S TT. Bought new in 1977 for $280 w/o arm. Added an SME 3009 and a MicroAcoustics 2002 cartridge. Presently have a Grace 707 and Denon 103 on it, along with a Hiraoka SE-22 mat (bought new in '78 for $20 from Harvey Sound, NYC). The Ariston/SME was purchased from Audiocom in Old Greenwich, CT (best HiFi store in Fairfield County).

My listening room :-)

That would be my Pioneer Elite PD-65 CDP. I bought it around 1992-93. With all the reasonably priced DAC's available today, it now does duty as a transport. The thing is a tank.