First tube preamp recommendations (under $5k)

How about a restored AR SP-3? Steve Guttenberg seems to like his...: https://www.youtube.com/watch?v=ImDH4k5LrlM

There is one on eBay right now: https://www.ebay.com/itm/294197206930?mkevt=1&mkcid=1&mkrid=711-53200-19255-0&campid=533...

New:   Audible Illusions M3B.   Best value for the money and meets your budget.

Used:   Upper end CJ or Audio Research Ref Series, or SP-10II / SP-11

Vintage:  Mac or Marantz

Benefit to used or vintage is the ability to resell for your cost (or maybe a little more).  Easy to try then decide if you like it.  If not- you can move on to another preamp.

My experience:  I own a ARC SP-10mkII and AI M3B.  BOTH sound GREAT, with with different virtues.

M3B   DEAD quiet- I can not hear it when it is on.  Soundstage is wide, deep and detailed.  MM Phono stage is excellent.   Very natural sound.  Dual stepped volume controls sometimes makes exact channel matching difficult.  But over time you find the (personal) gain setting that works best.

SP-10mkii   Slight noise floor.  Excellent phono stage with multiple loading choices.  Soundstage is wide, deep and detailed.  Overall sound is slightly lush and more tube like than the M3B.  May not be as accurate, but I like it just the same, and in some areas it sounds better.

Macro view is your expectations and budget are realistic so that you can explore the sweet spot of the market.

here's an alternative tact - use tubes in your source rather than the pre.
I'm not sure what pre you are using but keep it and try a Lampizator Baltic #3 dac instead of the Denafrips.  It may give you all the tube goodness you are looking for.

You need to audition the Backert Labs Rhumba 1.3. If $5k is the goal, then go with the Extreme version.

I couldn't be happier with my Sonic Frontier Line 2.  bought used.  solidly built.  very serviceable - Parts Connection.  XLR in and out.  dead silent. IR remote.  this was my first Tube pre-amp so i can't say as i have any comparison to others.