Need some recommendations on Tube Preamps

I'm using an Eastern Electronic MiniMax pre with my Krell KAV-250a to drive my Mg1.6's. Sounds glorious!

conrad johnson, any you can afford.

Glad to see opera is appreciated here by a goner.
If I may, I would like to make a suggestion: get the source right first before making changes down the chain. You will not regret it. Hope your source is vinyl, otherwise whatever the source is I would suggest bring it to the highest level you can afford. You will be shocked at how no matter what level your amp and preamp are at, a good source will be more beneficial then upgrading the other components.
When you decide to upgrade the amp and pre later on, you will be doing it knowing your source is to your liking.
An example may help convey the significance of what I am describing. I was considering a few upgrades in the recent past. One of them was to get a better speaker some time in the future. But for the time-being I was upgrading my turntable and phono stage. It was just a matter of time and a number of tweeks that I started to realize that my speakers were much better than I had thought. All this planning to get better speakers was due to not having a source good enough, but now I am only planning on making the source even better!
If in realestate they say location location location, in audiophile it would be source source source!

I want to thank all of you who responded to my query! I am greatful for the information. Most of you here would probably think I am lost in space!!! My main source is...prepare yourselves...An IPOD! Yes I know what you are thinking I am completely nuts!!! For soundstage I am completely with you on the fact that my source is mediocur however having gone through CD's and LP's years pass I find myself looking for simpler things in life and far less clutter. If i would describe me it would be "Salad bar"! I love variety and convenience. HAving to change an album or cd is such a pain. The 160gig Ipod can support over 4000 songs even at a wave file compression. Although not even close to a cd or lp the opera I listen to does have a lesser soundstage. CD reproduction is far better even with my panasonic dvd/cd player! I will look at two things first, CD source perhaps Rega Apollo and Subwoofer maybe Revel, REL or Velodyne. Later on I may invest in a Tube amp and preamp. Bryston lovers out there look out for my stuff being sold soon!!! Thanks