Entry Level Tube Preamp or Higher Quality Used Model?

I'm certainly overwhelmed with all o f the helpful answers. Thanks all!

The more I read about my particular power amplifier - the more I hear that it makes a big difference when you go balanced over a SE connection. 

It kind of puts me at an Audio Research model. I'm just a little shy about buying an older preamp and having it become a "project." For years I ran an old Mercedes as a daily driver. But in the end, the constant attention it required wore me down. I know this is a much simpler device... but there you have it. 

If I decide to go Audio Research, are there any models to shoot for or avoid? Also, I see that they seem to be re-capped (or not). How often does that need to be done and what should I expect to pay to have it done? That way if I find one that is in good shape otherwise but needs re-capping, I can figure that into the mix.  

If you want balanced connections and don’t need a phono preamp I recommend buying the Aesthetix Calypso. Unlike the Audio Research, and models from many other companies, the Aesthetix is and will continue to be serviced by Aexthetix. Instead of introducing a new model every year or so Aesthetix continues to improve their product and offer upgrades to current specifications if you want the upgrades.

+1 on the Calypso, though it would be helpful to know what amp you are using.

I will take a look at the Calypso. My amp is a PS Audio Stellar S300.

I would also look for a model that does not run the signal and/or rectifier tubes hard as even well reviewed current production tubes are not inexpensive (plus the hassle of purchasing/replacing them).

If you want to roll tubes, for different sonics, avoid anything limited to using the 6H30 (super tube).

DeKay