I have a secondhand Kenwood KA-3020SE amp on my desk from the 90s. PDF service manual containing the schematics and all. The thing is still perfectly usable, despite the relays for Output B needing replacement, and the input switching knob needing a good clean. The prominent, physical volume knob is a pleasure to use, and the 1/4 headphone jack's output power beats everything else in my house.

I have a problem though. It's absolutely massive, and I'm pretty constrained with desk space. But I haven't found anything remotely capable of replacing it. Given how I came to possess the amp in the first place, I'm pretty sure it's been through several owners before getting to me - and it'd be nice if the next owner had an interest in continuing to care for it.

If I do replace it though, I doubt the next one will last as long as this has, seeing how modern stuff these days isn't always built to last