I'm getting a second over the ear headphone to compliment my HD650. I feel like the HD650 is great for rock music and most of the pop songs I have, but I want a little more speed, sound stage, and treble for my EDM songs. I was able to get the 880 600 ohm at a recent amazon sale for $220, and the HE-400 right now is $300 at amazon as well. Given both are at extremely good prices, I thought this would be a great opportunity for me to expand my repertoire.
For EDM, I like somewhat of a U-shaped spectrum. I love listening to my EDM collection with my Westone 3 IEM's, so something like that would be great. I've read some reviews of the 880's vs the HE-400's, and each has its advantages and disadvantages. My main gripe with the 880's is that the bass might be not make as much of an impact on EDM's, and bass would be very important to me, but it does have good sound stage and very neutral highs, meaning it would likely sound great with my classical music. The 880 is also probably going to be as comfortable on my head as my HD650's, and this is very important as well since I would like to wear them for long periods of time. The HE-400's have great bass, a slight U-shaped sound with increased treble, which is what I look for. I'm mainly concerned about its weight and comfort, and its more intimate soundstage like the HD650's. I mainly want something that contrasts and compliments the HD650, and not be too similar. Something good with both classical and EDM music, which I feel that the HD650's are not entirely perfect for. I don't really care about neutrality or transparency, and actually even prefer a more "fun" sound.