I don't suspect most will agree with me, but the HP100 was one of the most disappointing headphone purchases I've made in a while. Many claimed it was a fairly neutral headphone, which is why I purchased it. Yeah, it wasn't even close neutral...
My pair had bloated, overly emphasized bass. I'm also guessing it had pretty poor harmonic distortion in the lower regions (I'm wondering if the very rough looking response on the published FR graph hints at that as well). It certainly had much more bass than my Mad Dog 3.2 (which is subjectively and objectively much more neutral when it comes to bass). It was even worse than my old Denon D2000.
The HP100 also had a huge suckout in the midrange. Even the HP100 FR graph provided on the box shows a 25dB dip just before the 2KHz point. It was pretty nasty on my pair and made everything sound off. I verified it through SineGen, and it matched up with the provided measurements.
The only redeeming quality of the HP100 was that its treble wasn't awful and didn't hurt my ears. It wasn't smooth, and it sounded artificial, but at least it didn't hurt my ears (can't say that for a lot of headphones, even those costing much more). But, again, the HP100's published FR graph shows a fairly lumpy response from 3KHz-10KHz. Do note that the scale of the graph is misleading. There's about a +/-5dB variation with each measured lump in the sound, or about 10dB from the trough to the peak of each lump.
I got better results from the $30 Monoprice 8323 headphone after some fairly simple mods: internal damping, foam in front of the driver (to even out treble response), and HM5 pads. Even then, I still preferred the stock 8323 over the HP100. Neither are close to being neutral, but at least the 8323 is appropriately priced.
If you like the HP100, that's fine. I can see why someone would like it. But my pair was not neutral in the slightest, which defeated the initial purpose of me buying it. Even still, no matter how I try to frame the headphone, I don't see it as a competitive headphone given the price point OR the sound quality. The accessories don't make up for that fact either.
Edited by hans030390 - 7/31/13 at 12:51am