First tube preamp recommendations (under $5k)

Should look at First Sound; new and/or used. Brady upgrade path to top of the line if you desire in the future.
https://www.firstsoundaudio.com/products

I would check out a pre-owned Conrad Johnson ET-5. It is essentially 1/2 of a CJ GAT1. It listed for $9,500 when discontinued a couple of years ago and are now available for $3,500 to $4,000.

This preamp uses a single 6922 tube, and it’s pretty easy on them, too. So, I run a Telefunken 6922. It sounds great with the Siemens 6922 tube, as well.

i am an owner of an et-5 as well, love it for its utterly beautiful, spacious sound and build quality, and the fact it runs a single tube, so tube rolling is effortless and cost effective

however, it is well known among owners of this unit that it runs the tube fairly hard (6.3 to 6.4v heater voltage, which is slightly above the spec for a standard spec 6dj8 tube) - so that tube will typically get noisy after about 1 year of regular use

there are solutions to this issue but i did not want those folks who may be considering the et-5 to believe that the single small signal tube will last as long as other tube linestages

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as a separate note, to the other post... the audible illusion mod 3a is infamous for being very hard on its tubes, and for not being at all forgiving of even slightly noisy tubes... furthermore their customer service over the years has been spotty at best... that unit sounds lovely when it is working right, but there are some issues/challenges to long term ownership

The vast majority of Audiophiles donot know what’s inside or the parts quality,did you know on average only 25% of your amp,or preamp cost $ is all that goes into your commercial brand ? The rest overhead and markup , that's why many have their equipment modded .that's how Dan Modwright made it popular.
for tube Gear I have used Radu Tarta one of the best Vacuum tube experts in North America hand built and with Premium parts throughout that is the difference ,and  with or without remote which for a top quality resistive remote  $400 ,not like most using a cheap $25 Alps volume pot,big loss of fine detail,and transformers and chokes are the key ,Lundahl,and  Monolith ,much better precision then lesser capacitor based output stage . In this case built one at a time and 70%of the cost  go into the parts ,in name brands it’s just the opposite 30% or less 
I have  found this out years ago , He Builds low power SET amplifiers, and DHT Tube preamps, only 1 gain stage which is the purist.most have multiple stages.

has anyone noticed the price of used Shindo preamps?  
not even close to the OPs budget- if you can find one.  

+1 Modwright LS100.  You can pick up one with optional tube phono stage for 1/2 your budget.  I run a McIntosh C500T in my main rig and I am shocked at how well the Modwright 100 performs in my second rig.