What qualities stand out in really good solid state preamps?

Really comes down to what sound characteristics you’re looking for, but if I was to boil it down to one word it’d be refinement. Specifically, a pre that is naturally detailed and not harsh or etched along with being well balanced and offering good tonality. 3D soundstage is a strength of tubes, so to the extent you can get a good dose of that in a SS pre that’d be a big plus. I think a good example of such things, and given that you were looking at the Herron, something like this Ayre would be in the ballpark…

https://www.audiogon.com/listings/lisb88c9-ayre-acoustics-k-5xe-mp-stereo-preamplifier-56586-solid-state

Hope this helps somewhat, and best of luck in your search.

@hilde45 I want my SS preamp to not add anything to the sound. I have 3 preamps and 2 of then adhere to the non-additive principle.

• Benchmark LA4 (30-day home trial)
• Holo Serene

You are not going to find anything quieter than these 2, except the much lower quality Topping pre90 (I also owned it). There was an online review somewhere that compared the 2 units. The reviewer preferred the Serene over the LA4 though he was splitting hairs. I prefer the better functionality and the slighter more neutral sound of the LA4. Both are exactly what I want in a SS preamp.

I also have the latest Schitt Mjolnir preamp (Class A). It is supposed to be their best ever preamp. I used to have the Freya+ and I like the Mjolnir much more than the Freya+. I use the Mjolnir with the Schitt Aegir amp for my RAAL headphones (or I used to, not sure if that will continue).

The Mjolnir is a good preamp that adds color where as the other 2 are great preamps.

A SS preamp that is tube like is the CODA 07x preamp (sort of like the Mjolnir). I owned that at the same time as the LA4. I decided that I wanted neutrality over tubiness in my 2-channel rigs. I use tubes on headphones (why the Mjolnir may not be needed anymore).

@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.