Tube sound simulating circuit using LS844 matched JFETs need help

[adason]

More...
https://www.pe2bz.philpem.me.uk/Mis.../Info-102-JFET-AudioPreAmp-Design/jfetamp.htm

 

[Citizen124032]

How about this simple circuit?
https://www.tnt-audio.com/clinica/preamble.html

Smart! Id = ( 1 - Vgs/Vpo)exp2 * Idss, so the 'squared' current Id is buffered as the output.