I agree a lot with @dover about high end not co-relating with sound of real music.
When it comes to phonostage, what makes it high end exactly?
RIAA accuracy? It is a given. In fact most phonostages have very low RIAA deviation (even entry level ones)
Resolution? Yea that definitely costs more and depends on quality of parts
Dynamics? Thats a big one. The factor which seperates the men from boys is dynamic range. High end phonostages today have the ability of startle with lifelike explosive dynamics which is one of the reasons vinyls sound so much more special than digital. I am yet to come across any vintage phonostage which has that kind of dynamics. They all sound mid-fi in the dynamic range department.
I don't think upgrading some parts with better quality equivalents of today is going to bring it to the level of a big boy dynamics of a Pass Labs XP27 or Burmester PH100. It is the circuit and design with big PSUs to provide that drive and DR. These kind of elaborate designs I don't see in the past.

