Chinesekiwi said it all a few posts earlier: there is no difference in detail between 880/250 and 880/600 ... the 880/600 is simply the better sounding HP.
Maybe overkill for movies. BTW, as you suggest, I watch movies with my 880/250 and listen to music with my 880/600, but that's because the 880/250 is the HP supported by my beyer Headzone, which does 5.1 DTS and Dolby thru the headphones that will amaze you, using a headtracker (motion tracker) connected to the headband of the 880/250. This has got to be more realistic than the JVC. We're not talking Smyth realism, but for movies it is spot on if you can sit dead center.
Unfortunately I will be using the JVC SU-DH1 as both DAC and amp(ish) for a couple of months. But as I am coming from a pair of px100s, hopefully I will still get lots of enjoyment out of them.
When I get the money together, I'm thinking about the Woo Audio 3+, along with a Keces 131 mk2 DAC. Of course I can't expect anybody to have tried this exact combo, but does this seem like combination that could work? It's hard(impossible) to tell what might be too smooth, or what will have nice synergy etc, so thought I would ask.
Other amps I have been looking at include the Little Dot MkIV, as well as the Darkvoice 3322, but I am leaning towards the Woo for some reason. It could be the one that sticks out in all the comments I have read, but maybe it's just it's heft.