What qualities stand out in really good solid state preamps?

@soix 

"...everyone needs to define that inherently indefinable neutrality for themselves. I think this is a big part of the art — and wonderful, awful struggle— of ultimately putting together a great-sounding system." 

Great point.  The "struggle" part comes in when people chase some sort of holy grail of sound by constantly "upgrading" to equipment that others report to deliver "neutral" sound, when instead, they should simply trust their own ears and stick with the gear that sounds the most "natural" (i.e., good) to them.

@decooney I have only auditioned the XP-12 in my home and can’t speak to the characteristics of the higher end or older Pass models. 
 

i agree with your observation that people sometimes upgrade only to wish they hadn’t sold or given away a piece of gear. Some folks on this forum post of having repurchased a piece they’d had before. 
 

Many of us get upgraditis. I’ve auditioned gear in my home that I thought sounded better only to find I couldn’t justify the additional cost for the incremental improvement. In one instance a dealer loaned me an excellent Luxman amp. I brought it hone and it sounded great until I put on a large symphonic piece and it couldn’t handle the power requirements of the transients and started audibly clipping! The dealer concluded it was likely because of the 86 dB efficiency of my 4 ohm speakers that drop to 3 ohms at some frequencies. It’s just another reason to audition gear in your home with your other equipment. 
 

@sameyers1 response to socks

Everything on the forum is opinion and based on individual experiences. You can say I’m arrogant. I can say you’d do better to not to get angry and recognize everyone’s right to post their thoughts and find a respectful way to disagree. I hope you can accept my response in the spirit in which it is offered, as a further explanation of how I characterize neutral.

You are much, much too nice.

Neutrality is an acoustics concept BEFORE being used in gear design...

The sound experience is an acoustics experience first and last....

There is too much variations in price levels and needs and synergetical variations to define a rule valuable for all systems,speaking about preamplifications...

People as usual gave their take on the branded named preamplification of choice... Why not ?

But it will be acoustics knowledge ( not only room acoustic) that will matter as much as gear synergy if you have a budget...

What qualities stand out in really good solid state preamps?

in my book for solid state pre’s is that they first and foremost do not damage the music signal going through them

then it would be the ability to adjust and maintain volume level by each input (to allow useful a/b comparisons)