I have never felt there were changes from one moment to the next. I have had first Quad els57s and later Quad 2805 speakers, and they have always sounded the same from one day to the next. The 2805s were an improvement, but in the same family. After a while with the 2805s I decided I needed a more powerful amplifier than the Quad 303, so I acquired a refurbished Quad 606-2, and that was indeed better, but every single day, and not varying from one day to the next.
I do agree with Shadorne that buying gear that professionals also use is a good way to proceed. Tony Faulkner, the famous classical sound engineer, also uses Quad stats for his recordings. My small system uses Harbeth P3ESRs. The British Library’s sound archive uses Harbeth speakers for their recording and transcription work. Neither of them go for audiophile tweaks. They know better.
I do agree with Shadorne that buying gear that professionals also use is a good way to proceed. Tony Faulkner, the famous classical sound engineer, also uses Quad stats for his recordings. My small system uses Harbeth P3ESRs. The British Library’s sound archive uses Harbeth speakers for their recording and transcription work. Neither of them go for audiophile tweaks. They know better.