This is just an idea, I wonder if it is possible?
I read in the last number of Stereophile about the Placette passive volume control. It is a stepped volume control with 125 steps and Vishay resistors, remotely controlled. Intended to be used instead of a preamp.
Would it be possible to bypass the volume control of a headphone amp and use this one instead? Of couse, some soldering is needed, but is it an easy or complicated operation.
Advantages should be improved sound quality and easy operation of volume. Many other stepped volume controls seem to have too few steps.
I don't know the volume control in question but it should be possible, you would just need a headphone amplifer with no volume control. Otherwise, I think you would be degrading the sound by passing it through two volume controls. I know at least one member had a Gilmore Reference built without the volume control so it could be used in the manner you suggest.