Do I even need a dedicated stereo preamp?

Get Return Privilege's for anything you try, compare, don't lose all the conveniences/features of something you have until you hear an improvement.

That's a good idea. 

If you are looking for resolution and transparency the Benchmark LA4 should be on your list.  This is the pre-amp in my main system

It is as close to a straight wire with gain (or attenuation) as you will find.  That and your amp should let the sound from your DAC flow through.

It is sold direct, and Benchmark do allow returns.

You've received a lot of advice along the lines of "buy xxx, it's what I use and will sound fantastic!"  However, in looking at your system, it seems rather piecemeal, and simply adding another piece won't necessarily give you better sound than what you already have.  Save your money for now, especially since you admit it is tight.  Plan on an upgrade that will upgrade your entire amplifier chain, either with a high quality integrated, or separate preamp and amp that play well together (they don't all).  Then work up from there on your other components.  Treat it as a lifetime hobby, not just a "do it once and done" effort.

I agree with several comments above, your system is not lending itself to inserting a preamp - however fancy - to make a significant difference. My favorite setup is SS power amp, tube preamp. which you can accomplish from 2K used - to replace your Buckeye. It would sure be different but not necessarily better. Nine words that applies to 9 out of 10 "upgrades" in this hobby.

My favorite setup is SS power amp, tube preamp. which you can accomplish from 2K used - to replace your Buckeye.

Is there something wrong with my Buckeye? From the start, I wanted more clarity and transparency than the class A/B in the anthem, and the Buckeye achieved that. Then I wanted a better streamer/dac and the eversolo took care of that. Now I’m really enjoying the cyan 2 R2R DAC. Music just sounds more enjoyable and less fatiguing regardless of volume.