I have tried about 220 different pairs of headphones over the past 3 months and have come to observe a few things.
1. Deeper cups tend to be common amongst the better bass cans and some audiophile ones such as Denon/Fostex
2. Hard shell cups/driver backing allow for more energy to be put to the drivers before the resonance of plastic shells interfere with the drivers low end signal.
My 2 favorite cans have aluminum/gunmetal aluminum backing and the Ultrasone Edition 8 has a superior bass to the Pro 900 (IMO) because the 900 suffers from a resonating vibration of the cups at high amp that the "Ruthenium" do not seem to suffer.
Sorry if I'm stating the obvious but most don't seem to put much into cup material or depth when considering high amp/ bass impact can hunting...though they seem to be related by solid housing and often deeper cups.