Help in choosing a potentiometer as a "Passive preamplifier"

Update:

Some time doing research seems to suggest that series resistor should be half of shunt. Also series resistor as low as possible, like 33K or less for input to a valve stage. Ideally much less. Found some comments:

A reasonable load for any normal line driving stage is:

Most can cope with driving 10k to 100k.

Some will cope with driving 2k to 10k.

Very few will be able to drive less than 2k, but some op-amps can.

34k input resistor value is a bit high. I like to do 50~70% pot value for input resistor value so loudness at 12 o'clock is about the same as a normal pot. Also did the Shunt mod today on my 50k pot tested with 25k and 47k, and 33k has a better control of the volume.

91k to 191k for a 100k pot, 47k to 97k for a 50k pot, 18k to 38k for a 20k pot. I'd recommend going Vishay Z foil VAR (thru hole), VSM (surface mount). It will be well worth the extra.
 
I have followed the recommendations by Gold Point for this type of adjustment.
 

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