I have had great experiences with small companies. Better than most big companies to be honest. Sorry you lost confidence in those guys
I had a custom amp built, it was the best experience ever. It didn't come with a manual, it's pretty straight forward. Input 1 , Input 2 , Gain, Speaker Jacks, Impedance Switch... Lifetime warranty. If I text or email the builder with a question he gets right back to me. He is actually building me a companion preamp for the amp he built me. It's about as Bespoke of an experience than you are likely to find anywhere. I had no absolutely no reservations about having him build me another piece.
My DAC is from a small company with decent support given it's size . Best sounding digital source I've owned . 5 year warranty. They are on a roll with a bunch of great products, no doubt they will be around for a while
I expect both companies to be around for a while, I'm 55 ... I could expire before either one ....
I'll use Zesto as an example. I owned their Leto preamp . I bought a demo unit, years out of warranty. Someone , not me, whacked a tube laterally and damaged the tube socket. The customer service was exceptional. They are a small company but they are very responsive and are great people to deal with should you ever need service.