I have a feeling that the superb subbass of Audezes might be due to the great seal that its adhered pads have with the head. This is evident because if I run a 25 Hz sinewave tone through the HE400s, it responds well, but if I even lift the cups off my ears by a few millimetres, the tone suddenly disappears. This might mean that if the Hifiman pads are sealed better, like how Audeze does their pads, the subbass extension will be close~equal.
based on the FR graphs alone, the LCD's do have a better response in the far sub-bass region. i've only demoed the LCD2's and although i feel they sounded slightly better overall than my HE400's if we factor price into it the 400's are drastically superior!
i do agree with you on the "seal" of the cups...i also notice that positioning on my head can make quite a difference in the sound. i've ordered some velour pads to try (i'm using the pleather that came with) but overall i'm not dissatisfied at all with the bass from my 400's,
IMO in this level of headphone I don't want a "basshead" can i want good response over the spectrum, which i strongly feel the 400's are providing...