Just wandering would the sound be better if you avoid the signal going thru the pot as shown in the schematic. Instead with a series shunt to ground config I think the signal goes thru a good quality resistor instead.see:
www.lara.on.ca/~gandalf/
www.siteswithstyle.com/voltsecond/12_posistion_shunt/12_Position_Pure_Shunt.html
www.audiosold.com/passivepre.htm
cheers
Paul