I've got the HE400 rev 2 and I wouldn't call it a monster bass at all... It has a decent bass level but far from over powering.
The treble and mid range level detail is good.... I've been doing a/b samples of the He400 with my new Audeze LCD2's and I actually prefer the sound stage of the HE400..... The Audeze are clearer, more detailed throughout the full spectrum, better on technicalities.... but listening to different genres.... smashing pumpkins, Gorillaz, Creedence Clearwater, Otis Redding, Muse, Rise Against.... I honestly think the HE400's offer a warmer, richer more "live" presentation..... with Smashing Pumpkins CD "ripped to FLAC" it was night and day.... the Audeze provided all the minutia level details and were very very good, but the HE400 felts more full bodied and the sound stage felt more real/ live.
If the Audeze seemed like listening through detail oriented monitors at the recording studio, the HE400's felt like listening to them at a live performance.
My Ultrasone Pro900's.... now those provide an overwhelming bass..... super fun.... but of the three I honestly see the HE400 as my best all rounder.... I hope I don't get descended upon by the audiophile community for suggesting I prefer the entry level Hifiman over the $1k flagship planar from Audeze but from a "enjoying music" perspective.... The HE400's are my most versatile and my goto.