Preamp to pair with an Adcom GFA-555 mkII

Hi, I have an Adcom GFA-555 mkII amp, and a pair of NHT Super Ones. I'd like to hear opinions on what type of preamp would pair well with them. I love clear detailed vocals with little coloration, and a wide soundstage. I listen to a mix of music, rock, r&b, jazz, classical. Any ideas? I'm also open to ideas on speakers. Oh, preamp budget is <$500; speakers <$300 (also need to be on the bookshelf or mini-monitor size). Thanks!
Your less than $500 cost point limits your choices.
I'd get a tube unit to help smooth out the Adcom.
There's a Audio Research LS1 for sale and a Counterpoint unit that might interest you.
Just pick one you think you might like. If it doesn't suit your needs you can always resell it without taking much of a beating if any at all.
I'd keep the speakers you have for >$300.

Preamp under $500 is tough. But I agree I'd go with tubes - it'll be hard to get smooth in solid state for that price point.
The B&K PT-3 or 5 is an excellent preamp and can be had used for around $200 or $300.
After re-reading my post... I did not mean choose either the LS1 or Counterpoint. They were merely used as examples of a quality unit... what I meant was, do a little research and simply choose a preamp that fails within your budget constraints and go for it.
Best pairing I've heard with the Adcom GFA-555II was the New York Audio Labs Minuet (not the Minuet in A). The Conrad Johnson PV5 was also a decent match. The Audio Research LS3 worked great in some systems, but could be a bit bright in others with the Adcom.
Acurus RL-11. It made a big difference with my 555-II over the Adcom GTP-450 preamp/tuner. I'm still using the RL-11 with my McCormack DNA-125.
Thanks for all the replies. The suggestions sound great, and I checked out the preamps suggested. I read elsewhere too that the LS-1 was a good match. I think I will stay with my NHTs too. If there are more suggestions for preamps, keep them coming, especially those with phono inputs.
I had a CJ PV10 with that amp and it was a great combination, CJ throughs a nice soundstage with a good but not excessive tube bloom. For me, the Adcom needed that.
I tend to favor the C-J PV10 over the LS-1. I've owned both and while I really loved the PV-10 for it's musicality, I felt that the LS-1 wasn't involving and sounded cold and sterile.