Yeah, I don't know if Akai went to a different factory to differentiate themselves or what, but as far as I can tell, the 50x is the only clone to retool the cups, change the L/R indicators, and change the pads. Every other copy has the same basic design as the original MDH9000, just with different printing on the band and/or cups and different etching on the aluminum caps.I can confirm that the Stellar Labs version also has the same bevel design on the rear of the cup. I opted to glue a flattened grille to the inside of the assembly after "opening up these delicious cans" . heh.
Interesting that you rolled to Brainwavz pads, as I did the same! Exception being that mine are of the pleather variety. I found it tamed the sound considerably after the modding process. They now have that wide sound stage.... and give a nice relaxed presentation of the music. Relaxed, but not lazy either. For me, the bass sufficient and not over powering with this combination.
I might have a weird set, but the Brainwavz pleather sealed too well, and paired with the open back, anything bassy gave me a headache as if I could actually feel the pressure waves. Hybrids broke the seal enough that I could listen comfortably.
I'm not sure how I feel about the open back mod. I picked up a set of Modern Retro to goof around with. Sound is okay, but soundstage is wiiiiiiiide. Figured I'd open up my HAS-30 to get something close, but nope, even open, they're nowhere as wide. That said, imaging is much better on the HAS-30, and the open back combined with hybrid pad reduces isolation enough that I can hear myself speak when using them as a headset. As far as I'm concerned, imaging + openness = a really nice set of gaming phones. A simple block with a ~10mm hole bored out, and I've got a flat panel to mount a mic to. Attached to the coiled cable, I can run the mic cable inside the coil, and I'm all set for a weekend of Monster Hunter.
As for boomy voices - that's not actually the headphone's fault (I learned the hard way that using good sources while testing is important). I'd set music aside and used the voices from an episode of NCIS to see how much I wanted to reduce bass. Turns out either my cable company has terribly compressed the audio, or the CBS audio techs just warm up the voices a bunch, but even on my 2.1 speaker amp, I can drop the crossover down to it's lowest value (the dial claims 50Hz, but I question the accuracy) and still have voices coming out of the subwoofer. Whoops.
For the sake of having a nice TV pair, though, I went ahead and inserted a teased cotton ball in each earcup. That dropped the bass enough to clear up those NCIS voices, but these definitely aren't bassy headphones anymore. Bass is still there, and *really* deep thuds nearing sub bass still come through fine, but I imagine mid bass is reduced in comparison to the stock HAS-30.