Vacuum tubed tone control???


Hello, I was wondering if anyone has manufactured a tubed tone control that could be put in-line between a cd player and preamp? I was hoping to add some musicality by rolling some NOS tubes into it, hopefully without hurting resolution too much.
talon4
A company called PSE used to make a hybrid pre-amp that had tone controls of an unusual design. As I understand it, the tone control switches somehow adjusted the current to the tubes as you switched them...which didn't interfere with the signal path...just changed the "flavor" of the sound a bit. (Please understand that I'm a complete idiot when it comes to comprehending electricity, so I may be describing this incorrectly.) I thought it was a great idea, and have one of the pre-amps, but apparently they're not made anymore.

I'd be curious if anybody knows more about this. Seems like a potentially fruitful area to work on, for those of us who (perhaps secretly) wish we still had tone controls, regardless of the high-end bias against them.
I've had the same dilemma, but, unfortunately, couldn't find a solution. Too lazy to fool around with cabling/tubes to serve as tone-controls. So,a Mac pre- is what I am going to get.