Preamp recommendation

Can pick up a used Sonic Frontiers SFL-1 linestage for $1000+/-. No remote but don't be a spud, get up and adjust the volume, lol. Change the single tube in the SFL-1 to the highest quality 12AT7 you can afford (I'm running a Genelex Gold Lion) and sit back and hear your amp for what it has to offer. I run mine with a Cary, 808R tuber and it's just fabulous match with my Equation, 7s... I also use it in a streaming setup but would not hesitate to grab a Lounge Audio or Graham Slee phono pre to complete the package in an analog system

I would certainly recommend my pre-amps, except for one detail:  I have only ever seen 4 for sale, ever, and I bought two and sold one of those. The other one was on a Canadian site.  So it does not matter.  Good Luck.  I recommend you listen and buy what you like to hear.  You are on a site with extremely prejudiced listeners, who often taut what they own to make themselves fell better.  Many are going deaf from age.  Visit a city with dealers.  They still exist.  To save money, if necessary, buy used, but listen first, somewhere.

W4S STP SE good choice should operate in passive mode for most  listening with your existing amp.

Quicksilver if you want tubes. In your price range hand built in the USA. Excellent preamp. 

Wyred-4-Sound STP-SE or Benchmark HPA4. Both use similar design philosophy. Can't go wrong with either.