help about Fetzer Valve

[Motifnick]

And I've made 3 fetzer , the 2 of this for preamp for my tda2030 homemade guitar amp and one stompbox edition..
my questions is..
1)the 100k trim i thing is too much ohm.. Because if I want to set it should do little and slight movement..It is a small point that works(if i put 10k or 22k is better? why not?)
2) power supply with clear sound?

[Seljer]

You can get multi-turn trimmers for critical adjustments