From tubes to solid state. What do you loose...

Brauser gives good advice. If you are hassled by a SF amp then you should back away at this point. Do the tube pre with NOS tubes mated to a SS amp and you'll be happy.

You want happy? Sell the SF and get a Supratek Chardonay pre, drop out the stock 6SN7's for VT231's, get a Pass or Plinius MkIII or higher amp and we'll never hear from you again.

I heard Judit's comments before. The explanation is not saying that you are adding harmonics, but rather the results of existing harmonics.

Music!

Brauser "took the words right outta my mouth. It must have been while he was kissin me..." Never mind.
I tried tubes and I really liked them after they broke-in and before they burned out. That was the best fifteen minutes of my life.
There are lots of good tube amps and pre-amps. There are lots of good SS amps and pre-amps. It's all what a person is used to. I have gone to SS and will never change, till later.

I have taken Asa's suggested route by pairing a Supratek Syrah and a Plinius SA-102. You can experiment with tubes--I have been happy with either Ken Rads(black glass) or Sylvania metal base (the latter tend to be a bit quirkier with noise). I realize it may be heresy to say so, but I have heard the highly-regarded Tenor amps in an excellent system and room, and I actually prefer my combination, which can be had at a small fraction of the price. Compromise, yes, but pretty damn close to all I can imagine hoping for. I would not trade my combo for the Tenors, I know that much.