Is it this
one?
Pretty intriguing and just pretty. Here is a link to the Vintage Knob
page. Plus it has had a cap replacement, another plus. Bit of a bummer it is a 100V version.
I owned a CL-35 MkIII for a short while had to move it on in a major relocation many moons ago. Mine was not recapped and had original tubes. To my ears it was on the warm and creamy side of SQ, similar to the old Mac preamps. This may be an entirely different animal. Know nothing about the Leben other than obviously it uses modern parts and would likely be the better sounding unit.
Mere tuppence.