im familiar with tube gear, and there are plenty of tube preamps for a grand, especially on USAM, and its a quick look thru what they got. theres some good new stuff, too. here are some suggestions:
used:
its 1200 new but under a grand used of course
https://avahifi.com/collections/preamplifiers
used VTA SP-14
quicksilver line stage...im not too familiar with it but its pretty damn popular
new:
Line 2CRM Line Preamplifier
https://www.mapletreeaudio.com/
tomcat audio
VTA sp-13