SET (single-ended triode) usually refers to power amps though a lot of preamps use triodes. Monoprice and PrimaLuna come to mind, or go used for something like Audio Research or Conrad Johnson (Lamm, etc.) I know Pro-Ject and others make tube preamps as well but I've never heard them. Another really good choice would be a new preamp from Frank Van Alstine, see http://avahifi.com/products/pre-amplifiers -- he has several around $1k that are probably really great based on what I heard from his stuff years ago. Plus he's a neat guy who's been around "forever". I'd give him serious consideration.
HTH - Don
"After silence, that which best expresses the inexpressible, is music" - Aldous Huxley