What qualities stand out in really good solid state preamps?

@yyzsantabarbara 
I want my SS preamp to not add anything to the sound. 

So there is nothing beyond tonality -- the only difference is warmth or tubiness vs. neutral/non-additive -- which matters for you?

If noise or quietness is the only factor for you, I am still stumped how you differentiate between preamps, other than the way they suit your tastes (color, functions) or create synergy with your existing equipment. 

@soix 
Thank you. Is "refinement" a way of saying "neutrality"?
Unlike others here, you mention soundstage, which I have heard is possible in SS preamps, though people associate it more with tubes. Others don't mention it. Maybe all the sound-staging and presentation of instruments sounds the same to them.

The Ayre has a great reputation -- I'm trying to find out which sonic attributes these famous preamps are known for -- beyond just being quiet or neutral.

@fuzztone  @mapman 
Another vote for neutrality or neutrality or lack of noise/distortion, etc. 

If you listened to 10 neutral preamps, would there be anything else sonically that would help you decide between them or would it all come down to non-sonic attributes?

Either there is nothing at stake except quietness/neutrality or there are additional descriptors not yet mentioned.

E.g. I recently compared two SS preamps. One was inexpensive, Chinese. The other was really great parts and design by a local DIY'er. Neither preamp added tonal "color" (i.e., tonal character, such as warmth) but they presented the music differently. In one, the soundstage was bigger, fuller (maybe not more detailed) and instruments and voices had more presence, body, realism -- that "in the room" quality. These were not mentioned by above posters, so I'm concerned that I am superimposing them onto what I'm hearing -- unless others have noticed these, too, but are just not mentioning them. 

So for me, sounds more like a Conrad Johnson than an Audio Research.  😁

I like colorful liars with excellent dynamics and imaging.  The midrange is especially important along with a treble that doesn't call attention to itself.

I'm less concerned with low noise, given my predilection for tube gear... but of course in a SS preamp I'd expect it to be dead quiet.

@hilde45 Exactly.  Just because a preamp can throw an expansive and transparent soundstage with properly placed performers left to right and front to back does not necessarily mean those performers are life-like with body and meat on the bones.  For me, it's a matter of 2-dimensional versus 3-dimensional images (performers) and what I am still trying to ascertain from those who own the Holo Serene KTE.  This solid state preamp is described as neutral, dynamic, transparent and very revealing but does it present the performers in a 3-dimensional way way with a body attached to their voice or instrument? I have owned the Ayre K-5xeMP mentioned above and it is an excellent preamp but it wasn't until I replaced it with the Ayre K-1xe that performers (images) had a more 3-D and round presentation in space. In short, the music was more believable (for me, in my room, with my equipment). So, tubes or solid state I am looking for the same things: a believable presentation of music by real performers in real space. LIVE is the reference.

pre-pump should provide enough pressure for the main pump first before anything else is desired.

@hilde45 After either listening or owning for a while about 1/2 dozen preamps, I found that warm preamps that add extra euphonic sound is unsatisfying to me, preamps such as a Coda 07x, Luxman c900u.

My goal is to let the preamp produce the sound of the amp, source, and cables without adding to the mix. My current Livingroom system has a warm amp with a slightly warm speaker. Adding a warm preamp to this would be a disaster for me.

Interestingly, my friend who is a huge tube guy and is currently building a tube preamp (to sell) that is going to cost more than any gear I own, loved my SS Holo Serene preamp connected to a SS CODA #16 amp. He was really hearing the CODA #16 + source + speakers. He was comparing my Livingroom speaker to speakers that were $600k 17 years ago.

In my office I have a Benchmark LA4 connected to a Sanders Magtech amp and Magnepan LRS+ speakers. The LRS+ is more on the neutral side, I let the Sanders dictate the sound of this system. For me that is easier to get the sound correct with less additions to the sonics.

The most satisfying thing for me was getting the positive feedback of my friend who is straight shooter and loved both systems. I told him before he came over to bring over a great tube preamp to my place because I thought he would hate my preamps. In the past, he hated some of my prior gear and told me issues I had with my small office system.

BTW - I sold my friends tube headphone amp to buy the Sanders Magtech. Now that I earned enough cash I bought back the tube headphone amp. I am not averse to tubes.