I'd agree with everything Mark says. To me, the Bernings have two major strengths: accurate tonal palette, and speed.
Tonally, they give width to trumpets and violins rather than the thin sound that can often be heard, whilst cellos, trombones, tenor saxophones etc. have a resonant "woody" texture to them. You could classify this as typically valve-like, but this accuracy extends deep into the bass.
Speed-wise, the Bernings are lightening-quick and in that sense more SS-like. Listening to something like Rodrigo y Gabriella gives you huge insight into just how technically strong they are. This speed isn't driven by an emphasis on the leading edge of notes, and so isn't tiring to listen to. There is also plenty of air / space around instrumentation which helps too.
As such, it's hard to pigeon-hole them between SS and valve.
My comparison to Constellation was perhaps confusing - they sound quite different. They lack the speed of the Bernings but have a bit better solidity in the bass. Tonally they get quite close. I compared them back-to-back and chose the Bernings.
One amp I have heard since is the 5-series Soulution. I found the pre worked v well with the Bernings, but the power also impressed. It is the first amp I've heard that matches the Bernings for speed, and the bass is better defined with a bit more punch. Tonally they are also accurate but the Soulution has an overall darker tonality to it which I liked. The Bernings have a lighter touch to them and more air. This was the first time I've listened to the Bernings vs something else and came to the conclusion they were different but not necessarily better / worse.
I'm hoping to demo the CH A1 again along with the L1 at some stage soon.