The first preamp I ever bought was an ART Tube MP. It was noisy and picked up WBOS, but when I could get it to settle I could get an okay sound out of it for $30. Lately, I've seen a few threads about people putting good tubes into low end microphone preamps with pleasant results. One preamp with which people had varied but interesting results was the ART MPA Gold. Unlike many of ART's other products, the MPA isn't a starved-plate low voltage device. Well, let's just say that it has a high plate voltage setting which is noticeable in its effect on the sound. This reminds me of the recent Joemeeks: they're okay as is, but when you employ the "Iron" button, you've got yourself a pretty good piece of gear for not a lot of money.
The tubes with which the ART MPA comes with are terrible. They only say "China 12AX7B" on them. 'Nuff said. You can do better with almost any old $8 replacement tube. I went with a $19 JJ/Tesla 12AX7 (or "ECC83S") for one channel of the MPA, and with a $29 Tung Sol 12AX7 for the other (each with gold tips). Both are newly made tubes and sound decent: they certainly make the MPA a workable preamp with some good tone. The Tung Sol really works well with my Heil PR40 microphone, but I will probably upgrade the JJ to a GE NOS tube in the near future.
What I really like about the MPA is that for $300 you get two channels with plenty of clean gain and each has their own sweepable high pass filter and their own sweepable input impedance (up to 3k). The Heil PR40 is a really bright mic, and sometimes it needs to be slowed down a touch to a 2k impedance even though that's against the recommended ratios. With condensers, the sweepable impedance isn't as important as it is with dynamic microphones that I like to use.
My True Systems P-Solo has been replaced. While that unit is fantastic for guitars (both as a DI and for micing acoustic guitar) the ART MPA Gold is working for me, and I'm getting comments on my sound and more importantly my voice that I wasn't ever getting with the P-Solo. It feels funny going back to a brand that I started out with, but it's kind of fun having a piece of gear and tricking it out - customizing it for your own needs, and making it your own.
Next I guess I should get some cheesy stickers and rhinestones to put on it. Someone might mistake it for an Avalon then.