@lukaszwk You might try TubeDepot.com I don't know of anyone selling tubes in Chicago, but I'm sure they are there.
I would not regard the age of the preamp as having anything to do with tube condition! Who knows if the tubes were any good when they were first installed??
I would not regard the age of the preamp as having anything to do with tube condition! Who knows if the tubes were any good when they were first installed??