[AzraelDarkangel]

This is a thought experiment since I'm poor at the moment. Most headphone drivers I've seen are designed to be as small and thin as possible, this makes sense of course. To maintain high efficiency and light weight, they don't actually require long voice coils and huge magnets. However, I've been thinking from the perspective of the tendency for more bass and the common use of equalization. At the moment, ignore the issue of weight without getting too rediculous. I was thinking about the problem from the perspective of loudspeaker design and looking at full range drivers around 4" and smaller. From that perspective, you are using a driver that is designed for much more output than what you need next to your ear so you can easily equalize the low end for more bass. You could use for example:
http://www.madisoundspeakerstore.com/approx-3-fullrange/fostex-fe83en-3-full-range

Say mounted in a 2" deep tube for the sake of simplicity, open ended. If you want to get more rediculous but better sound, metal cone full range drivers at this size often have better definition and bass detail but resonance peaks in the upper end but combine with a high efficiency ribbon tweeter for awesome dynamics, but you need a crossover. For simplicity we will say 1st order around 4k. And the two drivers mounted in a mild "V" shape words the ear, open part of the V around 4-5" with sound absorbing material covering every hard surface with the wide range driver closer to the rear and tweeter closer to the front if that makes sense. Example drivers:
http://www.parts-express.com/celestion-an2775-2-3-4-full-range-compact-array-driver--294-2046#lblSimilarProduct
And
http://www.parts-express.com/aurum-cantus-ast2560-aero-striction-tweeter--276-440

Of course you can't power it off your iPod, need speaker terminals. Probably need a fair amount of equalization.

 

[linglingjr]

A lot of manufactures of dynamic drivers already try to make them as big as possible and advertise it that way:
http://www.head-fi.org/t/619187/headphones-with-unusually-large-drivers
 
Sony has their XB 1000 with 2.7 inch drivers but I think a big issue about using the speakers you linked would be comfort/ weight.  Planars like the Audezes have huge planar drivers, amazing low end and also have weight and comfort as their biggest weakness.  I think part of the goal in designing headphone drivers is to achieve as much surface area as possible while keeping it as thin/light as possible too not only to make it more efficient but also to cut down on weight of other components as well.  
 
EDIT: just two of those speakers and tweeters alone already weigh nearly twice as much as the lcd 2.  It'd be a lot of fun though.  

 

[AzraelDarkangel]

I may experiment with a pair of the Fostex speakers when I have a bit more money. The main reason I thought about this is that most of the headphone drivers I've seen are so under built compared to any decent full range speaker driver. Most headphone drivers are actually very similar to speaker dome tweeters in general construction, just with bigger surround and different tuning and such. LCD series is about 600 grams. You could use for example:
http://www.parts-express.com/tang-band-w3-1364sa-3-bamboo-cone-driver--264-844
3" with Neo magnet at 300 grams each, 600 grams for a pair, just a bit over for the headphone itself.

If you want to think of it this way, is speaker terms. Most headphones are like small cheap speakers most people would buy for their apartment. Perfectly fine for background music but tend to be stressed and distorted if you crank them. Using speaker drivers in headphones is like taking concert speakers made to play at up to 120db and putting them in your apartment. Sure you will never crank them past 95db, but because they are not being stressed at all, they will stay clean with amazing dynamics.