This is a very odd thread. Why do people want more bass in a perfectly balanced phone? If you desire more bass, plug in a Grado, or something specializing in more bass. Simple as that. Don't buy natural salt-free potato chips when you want Ruffles.
I cannot figure out why people want to change the sound of a phone to match the sound of another brand. I am already stuck in the trap of owning too many headphones. If I start owning too many amps, I'll go completely off the deep end. Thank God I cannot afford to do this. 10 different pairs of phones, 10 different amps, after all the experimenting how do you know anymore what music is supposed to sound like? After a while we just disappear up our own ass.
Headphones should be like loudspeakers, no? You don't buy a pair of loudspeakers then go running around buying different amps to get more bass out of them? Maybe "tune" them with cables or wire but let them keep their natural character. That's why they're built that way. Imagine owning 10 pair of loudspeakers and amps and spending your time hauling them in and out of your listening room in the quest for musical Nirvana? They'd have sent me off to the laughing academy decades ago.
Of course, if all this is fun, then go right ahead, better than giving the money to the gov't to waste.