Just drank the Kool-Aid myself, although ironically independently of this thread. Found this looking for mods to boost the comfort, and have spent half the day reading through everything.
I have been really happy with everything but the comfort and the bass. So i embarked on the bass mod to much success. Opened them up and took off the piece of tape (stuck it off to the side so I could reverse later on.), and then stuck in two pieces of foam from a pelican case we had laying around at work. They pretty much filled up the void, and required maybe an 1/8 of compression to get the screws to be able to start. Bass seems much more full, and I don't detect and boominess or anything some others have described. These headphones go properly low, close to if not as low as my XB500's.
The sound is great all around, enough that I can forgive the comfort for a while until I can get that sorted out as well. Vocals in particular just sound great.
As for the comfort I am going to take a good look through the phones I have sitting around at home and try to find some donor pads. I'm hoping to do the double pad to make these over ears if possible, otherwise looking for some slightly larger ear pads that will fit (the mdr-zx600 pads are just slightly to large fyi).
I bought these for use as my vacation headphones along with a biosciencegeek cmoy amp to give me something a little more portable than my work ( Quart Phone 95 X w/ modified Creek OBH-11) and home (superlux HD668B w/ Little Bear hybrid Tube Amp) setups. So far I have just had them hooked up to a C-Media usb headphone adapter and already they sound great. I can't wait to get them hooked up to some proper amplification. I tried to hook them up to my Creek amp but aparently the stock cable and my 1/4" adapter don't play together.
If I can readily get the comfort issue sorted out these will definently be my new go to home cans (not at work cause I need the open cans to be able to hear other people/phones/the intercom etc.
I am leaving on a trip for a week where these will get extensive airplane and hotel testing with both the cmoy amp, as well as the Go-Dap I just bought today (couldn't resist). I will report again when I get back.