What is the best phono preamp you have heard?

The "Best" Phono stage I have heard was a cross between two.

As was said before "the best" does not make sense because the rest of the system matters too much.
But anyway..... Back in the early 80's.....

I Really liked my ML-1 Levinson. It totally trashed all the Audio Research (The other High End company of the time) options out there.

Then again I was using a Fidelity Research FR1 Mk3 Phono cartridge and The ML-1 had a phono section option specifically for that cartridge.

(I miss that cartridge - I had it in a Cyrinx Arm on a Linn)

An "Equal" preamp to that one was my old ancient STAX preamp.
Well - the STAX I had was one of the last SRA-12S's made and the circuit was slightly different.
The STAX was quite modified by me - especially in the power supply sections. I also reduced the feedback in the phono section to increase it's gain enough for my FR1-MK3. Also changed a few capacitors.

Just the other day I found those STAX circuit boards. I was surprised to find I still had them.

When time allows I'll build it up again.

My preamp now is an Audible Illusions M3A.
Parts quality is outstanding and it doesn't really have a "Tube Sound" which gets me sick.
(I'll get flamed for that!!)

But - I'm not really a tube fan.
Every time I change tubes (even from the same batch of a tube buy) I have a different sounding preamp.
It's the nature of tubes - Their characteristics vary too much from unit to unit which puts different tubes at different operating points of their "gain curve".
To a lesser degree - JFETS have that same issue.
When I sold STAX - I listened to the 4 preamps we had and took home the best sounding one.

The ML-1's I've heard all sounded the same - they are bipolar based. Although "Beta" of bipolar transistors can vary quite a bit, the "Operating Point" of different bipolars in a circuit are quite predictable

I digressed

Vendetta Research SCP-2T, of which perhaps half a dozen exist.

Jeff Rowland Cadence sounds better even using entry level
table and cartridge than any other setup I have heard
regardless of the price
The music arrives from dead silent background
it is coherent and inner detail is to die for, the cleanest
Ive heard, but If you know Rowland gear you know what Im
talking about

I loved the Aesthetix Rhea. I ended up buying the Conrad Johnson EV1 though, and it's marvelous, especially at its price point. I haven't heard the Boulder yet, but from what people have told me it's the most amazing piece of gear on the planet. The local Boulder dealer, who also carries Aesthetix and BAT, told me point blank "Do yourself a favor and don't listen to the Boulder. It's THAT good."

So far the Hagerman Trumpet with NOS RCAs.