Most enduring audio purchase

What has stuck with you through thick and thin, through upgrades, and through downsizing?

For me it's easy- bought in 1985, used frequently, works perfectly- my Zerostat!

I'm on my 5th set of speakers since then, been through 4 amps and on my 2nd integrated, 6th CD player, 3 tuners, 3rd turntable, 6th cartridge, 5 preamps, 2 phono pres, 5 headphones ( and I adore my current headphones & headphone amp combo) but my Zerostat (red) rocks!