Best sounding,reliable, tube amp below $700 used

Cayin TA-30 integrated. Essentially the same as the Primaluna Prologue 2, but goes for $600 to $700 used on Agon. They sell really fast though.
Extremely well built, hand wired, can run in SET mode or 35wpc with EL-34 OR KT-88's. Very quiet and holographic.

Agree with Mwilson--QS Mini-Mite Monos are excellent for the price ($998 new, ~$650-700 used).

Thanks for the replies, I've read about the mini mites on an old post here, and also the Conrad-Johnson mv-55 seems to also have a lot of backers. Please keep the opinions going.

What type of speakers will the amp(s) be driving and what are their specs?

And what some tube amps that you've heard and liked along with others that you didn't?

Well, my system now is comprised of an Adcom GFP-750 preamp, and PSB Alpha speakers, but I will be replacing the PSB with Revel M12s in the near future.

As for amps that I've heard, I really havent heard that many, but I have liked the sound of the Krells and Levinsons. I've listeded to a Rotel integrated and wasnt too impressed with that. I also had a Marantz 2330 that was okay, but not outstanding. I seem to like systems that bring out a wide soundstage, and detailed vocals, especially female. Does that help at all?