What is a very nice sounding tube preamp?

Look at the Aesthetix Calypso.

Gill Audio Alana by Art Audio - There is a used one advertised for $2,200 on US Audio Mart. The seller also had an Art Audio Vinyl One that I purchased.

I own a Gill Alana and give it a high recommendation.

ditto the Aesthetix Calypso... so nice, I've owned it twice!

TRY TO GET THE JOULE ELECTRA LA 100 MK 2 IS WAS THE BEST
PRODUTION WITH PURIST AUDIO THERE ALSO WITH CARDAS WIRE
THE REASON IS THE FOLLOWING THE LA 100 CAME WITH 2 5751
1 SYLVANIA GAIN STAGE 1 RCA BLACK 3 MICAS FOR MU FOLOWER
BOTH 5751 MUSICAL INSTRUMENT TONALITY EXCELLENT WITH CORRECT
PRESENTATION WITH SYLVANIA 6350 AS A UPGRADE IS GOOD BUT NOT
ACURATE IN THE PRESETATION HERE IS THE PROBLEM REAL WITH 6350 ONCE THEY RUN OUT IS GONNA BE DIFICULT TO GET IT AND VERY PRICY IN THE 5751 THERE A LOT OUT THERE IN DIFERENT
PRODUCTION THE AVILABILITY IS ENDLESS A LOT I AM SERVICE
TECH FOR OVER 35 YEAR I USED TO OWNE THE 300 ME,LA150SE
JOULE ELECTRA THE LA 100 MK2 IS MY FAVORITE BESIDE MY COUNTERPOINT SA 5.1 IN WHITCH VERY UNRIABLE EVEN WITH THE UPGRADES ONCE YOU GET THE SA5 RUNNING ITS MAGICAL ONE WORD
OF ADVICE JOULE ELECTRA COMPANY HAVING SOME BIG PROBLEM
SUPPORT FROM JOULE IS NONE BY PHONE THE PERSON WHO ANSWER
DONT KNOW NOTHING ABOUT THE PRODUCT AND HE WILL TELL YOU
TO EMAIL JUD BARBER IN WHICH HE NEVER ANSWER THE EMAIL BUT
NO PROBLEM JOULE ELECTRA IS A RELIABLE PRODUCT AND EASY TO
FIX PARTS IS NO PROBLEM THEY AVIALABLE IN THE MARKET AND A GOOD SERVICE TECH(SPECIALIZED IN TUBES)GOOD LUCK I HOPE YOU GET ONE

Can't go wrong with ARC. Many in your price range used. There is benefit going with a long time industry leader in tube gear especially first time around in case customer service is needed at some point.

The VAC unit is very nice also.