Dali Megaline, I thought were at the top of the Dynamic drive speaker Nose bleed heap ? I would definitely put them at the top of the list if I was in the 40 k territory for sure. I know this guy is a pretty respected audio guy here, check out his system in link below, but maybe they need tubes, I would think the ML gear would be pretty awesome with them too. Of course they are huge line arrays probably about double the size of most the speakers mentioned here, but if you got the space and money anyway so what!
http://forum.audiogon.com/cgi-bin/fr.pl?vaslt&1022712214&read&keyw&zzalbert=porter
http://forum.audiogon.com/cgi-bin/fr.pl?vaslt&1022712214&read&keyw&zzalbert=porter