I've had my share of recalcitrant gear over the years, but I'll just talk about the stuff that's happened lately. My Mytek Brooklyn Bridge streamer/DAC sounded great and even had a very good phono input, but it went belly-up maybe two days after the warranty lapsed. Neither Mytek nor the folks I bought it from, M**** D****, wanted to touch it. This was even after I said I'd pay for shipping and out-of-warranty repair. In any case, ever since, the device has been a veritable brick, sitting silently in my garage. Its replacement, a Cambridge CXN, works fine. So does the old Moon phono step-up that I fished out of the closet so I could play my records.
And oh yeah, maybe just under a year ago my PS Audio AC junction box started to smoke. Luckily, my wife worked as a film editor and happened to possess a pro-level, movie industry replacement. And you know what? The replacement junction box garners me slightly better sound.
My Marantz CD/SACD player went south, as well. Also not long after the warranty expired. Then there were the bad set of tubes I got from Upscale Audio. But in sharp contrast to my other adventures in the high end world, Upscale Audio was jet-quick in sending out replacements. I love those guys!