What is the best phono preamp you have heard?

I think it depends very much on combinations. I do not think that, with many years and spending a lot of unnecessary money (of course, within my own financial means) pursuing the so call "best single" component per se, makes me realize that there is one such component exists but eventually to presume that the whole concept is just simply a business ball game. It is strictly a system dependence. You can have the so called "best Phono" but to a larger extent you have to consider the cartridge/s to go along with it. I feel that there isn't any single best PHONO STAGE to cater for different cartridge/arm/turntable/preamp combinations. If so, we will at least not to receive reviews on components. Even reviewers have to admit that their reference system has to be changed from time to time. More so, with careful notice, it is the combination of the whole system that got to be changed from time to time let alone the speakers. You can't simply find any reviewer to just to stick one best component and allow the rest of the system to evolve. So, I would advise that, with these forums, try to find out the musically satisfied combination of components from others and of which, it fits nicely within your financial capability.

Counterpoint SA-9 modified by Michael Elliott:
removing 2 SS buffers, changing to Dynamicaps, removing MC stage, changing output volume control to naked Vishays, changing to high impedence circuit to have tubes directly drive output volume control, better Diodes, changing electrolytics to Blackgates, adding circuit damping

All of these pay off in sound quality.

I have`nt heard them all.The Herron is superb,and so is the Aesthetix.I listened to the Manley for a week when it first became available,i was impressed,but not blown away.I sold my first Walker reference while i was doing all this listening,regretted it,bought another,and now i am a happy camper again.I am a tube freak too,but there is something about this Walker phonostage that is very satisfying.Now mind you,i did say i have`nt heard them all.

Though I do not have that much experience with tt would like to say that I have just acquired an ear 834 deluxe and am quite happy.

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