There are two ways to listen to a DT880 - without an amp, or with one.
 
Without an amp, the DT880 at 600 Ohms is pure and clean, and you're going to capture surprising highs backed with tasteful lows. The DT880 has never been a bass-monster; this headphone is not well suited for bass-heavy music like dub, hip-hop, and reggae. However, unamped, this headphone will satisfy only part of the time. Tunes that have louder volume will sound full and satisfying; laid-back tunes may seem that they need a little more punch. And volume means a lot for many tracks.
 
Amped, the situation changes entirely. (By "amped," I mean it's connected to either good-sounding computer, or a suitable portable amp.) Formerly wan music has detail and punch. Unlike some headphones, which can be picky with source material, the DT880 sounds appealing with a symphony, or playing an old demo tape.
 
But how does it compare to a world-class headphone like, say, Sennheiser's HD800? You might not be interested on putting down so much money for a pair of headphones, but the difference is obvious. There's more of a sense of space - thanks to the angled speaker design and bigger ear cups. There's more richness in the trebles, and more streamlined bass. Comparing the two headphones, you get a feeling for "the law of diminishing returns." At what point does a pair of headphones do the job well, and at a good price?
 
At DT880 costs around $300 new, under $200 used and in good condition. That's less than a fifth of the price of the HD800. It's a solid value.
 
But no matter the price, the DT880 (600 Ohms) demands some kind of amp to fully flesh out the sound. 

Although I also own a HD800, I'm keeping my AKG K701 for its combination of comfort and performance with classical music - in which it excels. Aside from the Beyer DT-880, the most comfortable headphone currently made, the K701 has plush velour pads (though users with bigger heads may prefer a larger phone). And the illusion of head space is equal to that of the DT880 and Senn HD800, making this phone easy to wear for extended periods of time. 
 
The bass (or rather, the relative absence) is the sticking point for many. I believe that the sound is nicely balanced, but there's no question that it struggles to manage music with a more assertive bass presence. The phones have a ribbed top, and automatically adjusts to one's head size; however, many users will need to change their orientation so the phones fit perfectly all the time. Not a problem for me, but others have even tried to fix matter themselves.
 
However, I believe that this has been my best stereo investment. And if you look at the sell lists, you'll always find discounted phones for as little as $210 - a steal, in my opinion - and sometimes even less.

The newly announced 4th generation has several promising updated features, including an improved display, more speed, and an even better OS. However, the 3G is so good that switching would take some serious thought. 
 
If you listen to music on the go, the iPod Touch is the device of choice. Clear sound in a variety of EQs (including flat), a long-lasting performance, and a famously elegant interface makes this more appealing the more you use it. Podcasts are a bonus, whether audio or video, and the range of games available makes it flexible for entertainment. I tend to use it mostly to watch TV shows and movies, and it's easy to keep a range of programs for your taste; I also watch subtitled movies, and there's an app for that, too. 
 
Video and gaming are the two areas where battery demands are most severe. I can watch three or so movies to the end before needing recharge, but a game like Real Racing saps the battery more quickly than one might like. I don't use the Touch too much fore wifi, but using the web also uses more power than you'd want. Reading a full web page on the Touch (or iPhone) is not convenient, but there are a few work-arounds - at least some of the time.
 
The Touch does so many things so well that it's no surprise that it's top-rated. Even the earbuds/microphone shows a real improvement in sound and performance. I use it from several minutes to hours every day, and syncing is effortless. 

I haven't had the chance to audition the new Audeze phones, but it would difficult to fault the sound and build quality of Senn's HD800 - a model that has been praised by some as the best dynamic headphone, ever. Given its reputation as top of Sennheiser line, and considering its price, it's a good idea to elevate expectations. This is a fine headphone - but there's a lot to expect. However, instead of regurgitating a fine review like Skylab - whose systematic evaluation covers the important points - it may be just as important to provide a more personal review of these phones.
 
What I Didn't Like
 
1. Weight. While I've owned heavier headphones (including all-wood designs), the HD800 is modestly heavy. Some of the wood/leather models compensate with a luxurious look and feel; that said, one can easily imagine wearing the HD800 for extended periods of time. Compared to the lightness of, say, an AKG-K701, which can be used alternately as ear-muffs, the HD800's heft leaves one feeling comfortable but truly comfortable.
 
2. Comfort. There's no question, Sennheiser has done an impressive job balancing sound and comfort. The padded cups don't exert too much pressure - but don't expect the feather lightness of a DT880 or AKG-K701. Your ears might feel a little hot after an extended listening session.
 
3. Cost. I don't intend to harp over the "value" issue; if you're paying a grand and a half for headphones, value probably isn't a paramount issue. That said, I believe you should at least sample the phones before making a decision. You might find that a dramatically cheaper phone would be more to your liking.
 
What I Liked
 
1. Detail. These phones emphasize quality bass and detailed mids, giving a convincing sense of accuracy. The more you spend on a pair of headphones, the more subtle the differences in sound; however, with the HD800, one comes away with the feeling that the music takes priority. It's detailed, but truly a generalist's headphone.
 
2. Brightness. It's easy to fall into the trap that the HD800 is a lighter-sounding headphone - when in fact it's extremely accurate. Don't expect a boomy bass; the HD800 sounds remarkably like well-mastered studio recordings. 
 
3. Build. As you'd expect, the HD-800 has a rock-solid build. To be honest, I'd prefer real metal over faux metal, but in terms of overall quality, these phones are reassuringly strong.
 
Conclusions?
 
There's probably no such thing as a "perfect" headphone, but the HD800 renders a variety of genres very well, indeed.