Do tubes matter beyond gain stage on preamp?

what i find interesting are the designers who are capable of working w both…. two come to mind … Vandersteen and Aesthetix..there are a lot more if we throw the use of FET as front end to tube phono stages, many many more….. 

@noromance yes! i have same neon and swap was meaningful, there are two “ hidden “ FET in my RS

Shall, I send it your way for the cold midwinter ?

Not sure why power supply tubes in a preamp impact harmonics?  Maybe cause it cleans up power.  If input components, eg streamer/phonostage, connected to preamp all have great power supply than preamp power tubes would seem less important.

If you add something to nothing you would have something instead of this nothing