Also, adding in an internal amp seems like a good idea, but the problem is that would just increase the signal. Yes the same effect would be achieved but at much higher volume, I suspect Skullcandy thought of that, and decided against it due to it being dangerous to the consumers. They wanted a specific effect and they got that effect that works even at reasonable volume.
That's a good point that I forgot to include; because of the Sensation 55 drivers, you can get some really thumping bass at low volumes. It sounds "off" and I usually had to bring the volume level up to match the bass. Never to uncomfortable levels, and never to distortion. The bass effect doesn't ramp linearly with volume as you'd expect. It does increase as volume increases, but the ramp up is different from the rest of the range.
I did manage to use these with an Fiio E6 and they sounded much better on EQ2. I returned both the E6 and Crushers before I could try them with a Digizoid.
Again, these are fantastic for non-audiophiles and specifically gamers; my 12-16 year old self would've been so stoked to get these for Christmas. I played Forza Horizon (an arcade/sim racing game hybrid) and it was nice to feel the rumble of the engines. I also played the Modern Warfare demo a bit and the rumble effect was nice when you throw grenades and shotgun blasts. And again, both genres sound better through my ATH-M50 + Astro Mixamp w/ Dolby Digital enabled + Z02. That's the closest to a home theater in headphone form I've ever experienced.
I really want an audiophile headphone maker to tackle having dedicated hardware for low-frequencies. I just can't imagine it happening because a well-tuned 45mm-50mm driver properly amped can get so close. But the Beats crowd could drive the market, as evident by Skullcandy trying to grab a bit of that market with these Crushers.