I am planning to go with EF-6, is should be safe bet. I am kind of frustrated with speaker amps. With speaker amps your entire rig has to have good synergy, dac->premap->power amp. And I would end up spending 3K and kind of risky with experiments high gain may blow up the HE-6.
with EF-6 and with simple balanced DAC (like emo DC-1).... if am able to get 80% SQ what preproman or brunk get out of their rigs, then it should safe bet in long run....I guess.
I thought about the EF-6 too and it would be easier to source in Europe and on the whole a lot cheaper to boot but I think there's more to be squeezed out of the 6. Painful process though...busy cancelling my FW F-3 purchase right now after what transpired about it earlier in the thread. I know myself, having decided to give a speaker amp a try to see if it really substantially improves performance I might as well go the whole hog and stop the 'what if' merry go round. Back to the drawing board for me. These cans are a ******* minefield and only suitable for people with a pronounced masochistic trait....I feel like a snail crawling over the edge of a straight razor (flashback to 'Apocalypse now').