Liking my Modi and Magni with these more and more each day. I feel like they're getting all the power they need, and some. I also cant, for the life of me, discern a difference between the Magni + attenuators and without (from a sound quality standpoint). The extra play on the volume knob is really nice with them in.
Been listening to a lot of video game music and chip-tune and it sounds great with the HE-400
I also love video game soundtracks a lot. KH,FF,Heavy rain, uncharted, Halo, Yakuza 3s, etc. OSTs for games are awesome very often, more so that you can connect the songs with the emotions and encounters you had within the game :D
I also listen to Chiptune... Wait, nevermind that is a different "Chip"tune you lisnte to :D