Amplifiers are not rocket science, especially Class A ones, literally ancient technology from 100 years ago. The reason why they are charging hundreds time more solely because of psychoacoustics / snake oil and beautiful designs. Chi-Fis are usually either fake tubes or legit tubes with poor QA. Nobsound literally selling tube amp self-assembly kits if u are into EE. Low end tubes sounds like crap because tubes are there only for lighting and they use inferior op-amps. High end tubes sounds like solid state amps because solid state amps are literally the next and better evolution of tube amps. There is no magic, it just ppl like distortions (even order harmonics) and psychological audio quality boost from hefty price tags and glowing tubes. Every aspect of that can be archive by a cheap SS amp and EQ.