Maybe tube preamp

A used Conrad Johnson pre at the OP's budget would be a pretty safe bet. First off you'll get a great taste of the virtue of tubes and if it doesn't appeal for whatever reason, doubtful at least from my perspective, an easy resell without any financial pain. These units really focus on the essence of music and I totally agree with suko, people take notice of the music, not "Man, your system sounds great"!  

I did say I would update this post with my decision.  2-1/2 years later I am looking at old posts and notice I neglected to do so.   I bought a Transcend 6SN7 line stage preamp from Aric Audio.  Turned out to be a good decision.   It added the warmth I was looking for without muddying things up.  As noted Aric was a pleasure to deal with.

I notice the Transcend 6SN7 is no longer offered on the AricAudio website, though he does offer a 'Special'  6SN7 line stage with a bunch of upgrades for $3500

Also to update, my Freya (original version) has been around here for a couple of years now and it's certainly the best 800 bucks I've ever spent on hifi gear. Various tubes have been tried, none including the original Russian something-or-others have been microphonic or noisy, and my current faves are NOS GE 6SN7GTBs...an amazingly transparent preamp that supplies zero motivation to replace it as it simply works perfectly and sounds beautiful. Or doesn't "sound" at all which is how a preamp should.