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