The primary Dark Eldar entertainment (among Kabalites anyway, I don't know about low commorites)
is the arena, they all go and watch visceral displays of violence. As for the technology involved, I remember in path of the renegade, The three noble archons were utilising some sort of tech to make it as if they were actually in the fray. I don't know if the DE trust each other enough to organize in a social setting without a Kabal to back them up.
(I am pretty proud of how many times I just put the word 'cape' in a post)