PSAudio GCC 250 that was moded as new. My original intent was to have it replace all my separates and simplify my life. Alas, it was not potent enough for my big room, so I moved it to my TV system
What, in your system, have you owned the longest?
For me, it's my Zerostat. Bought it in the '80s- most likely 1986 or 1987.