Modern "Vintage" Sounding Preamps

Audible Illusions

     Purchase most any tube preamp, and load it with NOS, British valves (Mullard, Brimar, Genelex/Gold Lion, etc), to get that vintage warmth.

     If that doesn't sufficiently warm your heart: replace the signal path resistors, with Carbon comps, starting at the inputs, until you're happy.

     Some Paper-In-Oil caps exhibit a cozy signature, as well, in the signal path (ie: to warm up a later model CJ pre, replace any white or yellow (Mylar), plastic wrapped caps).

     I had a few customers, that enjoyed that flavor and: "The customer always thinks they're right!"

     I was in business, to satisfy whatever palate walked in the door.

    Some ideas (soundwise), were you to find a nice 6SN7 pre, per tubes to choose:

                              http://www.audiotubes.com/6sn7.htm

     The nine-pin miniatures, from those companies, have the same attributes in my experience.

      If you want less warmth, with the minis: Those from around Holland, Belgium, etc, (ie: Amperex, Bugle Boy, Philips, etc) may suit you best.

     There's a ton of fun to be had, if you take up tube rolling.

     Even more, if you can (or learn to) solder.

     If you do go tube: before you purchase tubes, be certain they are tested and certified to be, as absolutely as possible, QUIET.

@rodman99999 is entirely correct. Loading any preamp with inexpensive Russian K40y-9 PIOs and Allen Bradley CC resistors will definitely steer you in the direction you want to head. K40y-9’s may have a strong enough signature to do it alone. The old style Jensens/Angelas are a pretty safe bet too but less reliable.

Top of the line 196P Sprague Vitamin Q‘ PIOs are on a different level and will probably not do what you want despite the folklore. As @rodrodman999999 says, it‘s all about flavouring.

If you don't mind my asking, why the 20 year cutoff date?

I have an ARC SP11 mk2 (1987) that sounds lovely and will likely keep sounding so for decades to come. Prior to that was an SP3-A1 from 1975 that many will agree still sounds wonderful and can be easily refreshed with new caps and tubes.

My point, is why buy a new preamp/design when you're looking for older sound?

That'd be like buying a modern car then retrofitting it with a hand crankstarter and narrow wheels for a 'vintage experience'. :)

Don't write off vintage equipment...

Happy listening.