You ask a good question. I have owned high end amps and preamps since the late 1970’s with Threshold being the first. I finally moved up to tube amps over the last decade.
Different people are looking for different sounds. Some want “high end” sound, which is often exaggerated treble and bass… transparent, highlighted detail, lots of slam and imaging. Lots of older high end solid state equipment has this sound… partially because it was not known how to get good mid-range bloom and great rhythm and pace in solid state into solid state.
This has been improving. Pass recognized this earlier than most with his XA series amps, Now much more natural sounding solid state amps are available from companies like Pass. Going back even ten years though you can loose much of the rhyth and pace.
Getting more natural / musical sound comes first from a good tube preamp… like Audio Research or Conrad Johnson. Then if you are unwilling to go to tubed amps, look at Pass x series or XA series.
There are lots of companies doing the less natural, “high end sounding amps”, like Luxman. There is also MacIntosh, who does powerful heavy midrange / bass amps with under emphasized detai and treble. These “muscle car” like amps are really good at rock music.