I'm pretty sure the HE-500, HE-560, and the HE-400 at least with mods can all extend just as deep (the Sundara too). All four of these headphones have quite different sound signatures though, with the HE-400i and HE-500 being the closest. The HE-400 has a V-shaped sound signature (boosted bass and treble, some mid range recession), the HE-400i is tuned to be rather neutral, the HE-500 is also neutral but maybe with slightly laid back treble, and the HE-560 is bright.