The only piece of gear I have owned in teh last 20 years that was a absolute clear bottleneck on good sound was a Carver pre-amp. I had Carver amp and tuner (still do) and the tuner was/is quite good and teh amp actually not bad if used properly.
A fellow audiogoner whose advice I trusted told me flat out dump teh pre-amp. So I did and replaced it with a Audio Research model.
I have had many changes since then each of which introduced a change in sound, mostly for the better. I have been in a very good place in relation to live music I hear and teh best "reference" systems I hear around for a number of years. That’s not to say there is probably almost always something one can do to get even better. It may or may not cost more. It all depends on educated decision making. Nothing great ever comes easy. How much it costs is another story and can vary widely. My $130 Fosi amp does a top notch job in its role on my little nearfield desktop system. Some day I may try to ask more of it and see how it sounds when given a much tougher job.