So I played with my new JVC HA-RX700 for around 10+ hours. My impressions so far:
THIS are electronic music headphones. RX700 has excellent performance on slow to medium fast genres of electronica like Tribal House, House, Drum and bass, RNB and (not vocal) trance. Sound is warm, with deep impactfull bass. On good recordings there is enough detail and trebles. On worse recordings sound is muddy and veiled. If there is not much going on, vocals are clear but on genres like vocal trance, vocals are confussed and lost in the bass.
I compared them to my DT880 32ohm powered by Xonar STX (Medium amplification setting). Music on RX700 is way more warm than on DT880, RX700 has more body but less mids and trebles. Music is FUN to listen (I mean electronic music).
I tried to play also some acoustic based music, and guitars, piano, etc sounds more real on DT880 but sometimes too thin. Vocals usually sound better on DT880 (openess of DT880 helps here lot).
Overall I think that RX700 is good complementary headphones to my DT880 for most electronica genres. For rock, and vocal music (vocal trance too) I still prefer DT880.
Here are some artists and genres that I tried so far:
N.O.H.A (drumm and bass with some vocals) - excellent on RX700, good on DT880
Prodigy - excellent on RX700, too thin and shrill on DT800
Metallica - average on RX700, good on DT880 (electric guitars had more energy on DT880)
Cranberries - folk/rock - good on RX700, excellent on DT880 (more detailes, real instruments, awesome vocals)
Armin Van Buuren, Dash Berlin - vocal trance tracks - muddy on RX700, excellent on DT880
DJ Tiesto - trance tracks - excellent on RX700, good on DT880
various Tribal House artists like Glender, Dj Carlos Manaca, De Leon - excellent on RX700, average on DT880
various mainstream popular dance music like Pitbull, David Guetta, Inna - great on RX700, good on DT880
So my conclusion:
RX700 is excellent headphone for most current popular mainstream electronic genres, when it delivers more than DT880. Comfort could be better but its acceptable.
DT880 is still more detailed, analytic headphone that sounds better on acoustic genres and vocal heavy music. Comfort is absolutely excellent.
For 44 Euros shipping included I am absolutely happy that I finaly found headphones for my electronic music - RX700.
Are they better headphones than DT880 32ohm which were 300 Euros shipped? No, but for bass heavy electronic music they are BETTER choice and more fun than DT880.