The notion that manufacturers secretly deliberately design their products to degrade, but only just enough to not cross a very fine threshold of degradation to avoid becoming obvious poor quality - is simply not realistic.
Often the question of whether one’s system ‘sounds best’ comes down to what might not exist within the soundstage.
In other words, when there is nothing obvious that offends the ear, the question becomes whether the speakers or a given piece of equipment might not be transmitting some or all of the source material as completely as can be done.
The question of what might not be there is nowhere near as straightforward as a poor soundstage no matter what you do, or a hum that shouldn’t be there.
For instance, my amplifier sounds really fine, but I have come to wonder if there exists more clarity and openness in the high range, so I’ll eventually try another.
And specifically, I wonder this because I’ve run different speakers on this system and studied their sound, I’ve got my set-up correct including cables, source devices are excellent, and I’ve done a lot of reading that suggests to me that there is better sound to be had.
Logically, it could be the preamp or the amp, but the amp is older, so I’ll start there.