"A friend of mine had the LFDs which he liked very much, he went to the Leben and found that he liked it better."
Apples and oranges you know.
Leben is a tubie whereas the Zero is SS. Also:
How much time did he take to adjust to the sonic character of one before going to the other? Did he roll tubes with the Leben? If so, to what? I rolled some GE 6CA7's and NOS Mullards into my Jolida 302 and it blew my mind how involving that integrated amp was - made it hard going back to the SS LFD, but I adjusted and love the LFD just as much in a different way - it's got balls for just 50-60 watts (you'd never believe it till you try one out). BTW: the Leben's aren't exactly chump change, that's big buckaroos gear.