Tube Preamp: How many tubes does it take to .................

I think that sound reproduction fidelity is inversely proportional to the number of gain devices.  So do a lot of people.  Accordingly, I don't think it's coincidence that the best sounding preamp that I've ever heard uses only one-half of a double triode tube per channel as the entirety of the gain structure.  It's the Dodd Battery Powered Preamp.  A simply extraordinary amplification device.  No voltage rectification.  Huge signal to noise ratio.  Remarkably linear and remarkably transparent.  There's a reason Danny Ritchie still uses one to demonstrate his speakers.  To paraphrase Danny: "If I knew of something better I'd use it, but I don't."