Sorry to hear you are having such bad luck. It is hard to believe some of it isn’t just bad luck.
High end equipment is normally tested extensively before shipment. With the exception of a Sonic Frontiers CD player which had an unreliable transport in it. I have never had a problem effecting to performance or function of a piece of equipment in fifty years. I have had some components for nearly twenty years.
Depending on the company, they often rely on dealers as their front line contacts. I have an outstanding dealer. He is there for me and has become a friend. He delivers and installs all equipment and makes sure it is working at optimum performance. So, he’ll set up the sampling rates, and any setting on my DAC, position my speakers, make sure all aspects of my turntable is perfect... etc. If I have a question he comes to my house.
Once a meter wasn’t registering correctly on my amp. So he came over, attempted to destatic it. That did not work, so he asked me if I wanted a new amp or him to replace the meter. I asked him what he thought... he said, "I’ll get you a new one". He actually called the vendor while we were standing there and in two minutes said, "the new one is being prepared for shipment." When he received it, he came over and swapped them. I did not have to lift a finger.