I think a large part of it is a case of perception. For example, if I drove the ELYSIUM through an amp, would I perceive a more stable, more out-of-head stage with more tactile instruments? Yes. But, would I be perfectly happy with the ELYSIUM driven by a DAP or a smartphone? I would, as well. So, some added juice is nice, and it's required to get the absolute best out of it, I feel. But, as far as getting it to show its quality, or getting it to live up to its price tag, I think portable sources can do it justice just as well.
As far as the physics of it go, I can't really say for sure what it is. I'd love to see what changes - in the treble, especially - when you give the ELYSIUM some power. But, to me, at least, it's definitely audible. I don't know if I mentioned it on this thread or not, but I did write a post about headroom and potential being different from volume. I can get the ELYSIUM perfectly loud out of my Lotoo PAW Gold Touch; albeit, with more clicks on the volume wheel than all my other IEMs. But, there's always the slightest hint of compression to its stage; again, not a flaw by any means, but a sign that it can do a bit better.
Again, though, at the end of the day, it all depends on what you can perceive, and what you're willing to give up for what. Whenever I listen to the ELYSIUM, I certainly don't make the effort to turn on my desktop amp and tie myself down to a chair to listen to it. I'd much rather listen to it conveniently through my DAP, even when I'm just sitting at home. So, yeah, the way I've always seen it is: You'll be able to drive the ELYSIUM just fine out of a portable set-up, and it'll offer you that extra level as a bonus should you ever wanna hook it up to more juice.
For a bolder, warmer, more soulful sound with those genres and male vocals, the VE8 surely takes my pick.