This is for Georgehifi especially but others can chime in.

Your statement " All passives basically suck" is your own problem with your system/amp gain structure. Live with it.

Cheers George

@georgehifi 
Uh... No... It's a cold, hard fact. Volume pots present a miserable impedance to a source and an amplifier, generally speaking. I could probably feed the F5 with one if I wanted because it's got a 100kOhm input impedance, but if you're dealing with an amp with a more typical 40-50kOhm input, putting a 25kOhm pot in front of it is just plain stupid unless your amp has low enough gain you can run close to wide open. Of course, then you present your source with a feeble impedance then. Sounds very imperfect to me. It's not a solution I'd briefly entertain, much less make my problem. 

You state "All passives basically suck".
  
You have a problem sunshine that you need to address before you can make such a statement.

You you say your power amp gain is only 15db, this is half of what most amps are and is not passive friendly.

Who said 25kohm passive??? You should not have tried 25kohm passive, should have been 10kohm, as this is a match for any poweramp with industry standard of 47kohm input impedance or higher, and your source hopefully is low output impedance, not high impedance tube. 


So basically you suck it up and don't even go passive and complain about them or you fix your problems and maybe just maybe you may see the light.
That passives can be more transparent more dynamic and less coloured than any active pre with or without gain.

Cheers George

@georgehifi 
Oh? You think 10kOhm is a great impedance for a source to be looking at? If you like nonlinear, volume-dependant sound, have at your passives all you like. Just don't tell me how uncolored they are because that's a demonstrably false statement.