@tjag said
Do you people ever do listening comparisons?
First of all, how dare you classify me as "you people"? You know nothing about me, you merely make yourself look small and mean.
Secondly - I do listening comparisons. I've also worked on thousands of different bits of audio kit using measuring tools - because it was my job! You cannot return a bit of repaired audio kit without first proving you've eliminated the reported problem and ears+brain are insufficient for that task, you have to use signal generators, meters and audio analysis kit. I also used to play some music to check all was OK.
I've encountered a great deal of genuinely faulty kit which still sounds OK-ish, ears+brain are a very low grade mechanism for checking things are not broken...