These are my favorite headphones. I've had them for years, I don't even remember when I bought them, but still to this day, every time I put them on, they put a big smile on my face.
I own headphones such as Sennheiser HD650 and AKG Q701, and have owned many others much more expensive than HD212's, but none of them were as fun.
HD212pro are in my opinion one of those headphones which make you forget about sound neutrality, or soundstage, or imaging, etc...they just make you have fun. Any music, from techno, dubstep, rock to classical and jazz sounds great for the money, and that constant smooth bass envelops you. No other cans that I have tried can produce as much bass as these. I mean, HD650's bass feels thin after listening to these for a while.
Overall, great set of cans for the money.
EDIT(May,2013) - after about 6 years of ownership, these headphones are physically in a bad condition. Earpads have started flaking, the foam has lost some of its firmness (but still far more durable than earpads on HD650's), the silver paint is on some areas now just black plastic, etc. But sound....sound is better than ever before. I've recently bought a Sony XB500 because I found them on a good discount, hoping it will be an upgrade over the HD212 as a basshead can. Well, its not. To put it nicely, XB500 sounds like crap next to the HD212pro. Yes, it has a bit more bass quantity, but nowhere near the quality. As for mids and highs...there is no comparison, HD212 outclass them. They sound like headphone that easily could cost twice or even three times as much. I'm honestly a believer than HD212pro's even at a price of 120 dollars would not be anything other than a excellent headphone. The amount of bass punch they manage to produce, and the way the bass is separated from the rest of the sound, makes them quite unique. I'm yet to hear a headphones that does it as well. Not even the DT770 Pro 80's manage to achieve such sound separation. Even though they are slightly superior in sound quality overall, they definitely don't outclass or humiliate the HD212pro's. These are simply stunning little headphones with a big sound. They NEVER EVER disappoint, but they need a amping. Yes, even though you can plug them into a phone and they'll get loud enough, using them with a proper source and amp makes a big differences. It transforms them from muddy bass heavy sound to a crisp, punchy, hard hitting sound. The voicing is also very good. They sound realistic, more than some much more expensive headphones. I'd go as far to say the voices when listening to podcasts or radio sound more real than on the HD650's. Not as clear of course, but its a "right" tonality. Its no wonder since they're basically flat (+- 3db) from 50 to 2000 Hz with a gentle roll of on both ends. Certainly "pro" headphones, even if they can produce loads of bass.
Overall, again, great cans. They're just so reliable and always make me smile. Its one of those headphones that after some time you forget about, because you've perhaps bought new headphones and you're using them, and you might throw these in a box and put them in a basement, or in some storage room, and after like a year or two while browsing for something, you find them, plug them in, and get absolutely amazing by how good they sound, and then end up using them for like a month straight without ever looking at your 400-500 dollar cans.
I cannot comment on the amp as while using these I was younger and was ignorant to such things, however if "properly amped", why would it distort? Wouldn't properly amped imply that the amp setup is ideal for the can, thus this makes no sense??
In any case I am sorry you feel this way, I had a very different experience with them and they are responsible for my now expensive habit