Very interesting thread! After reading through it, my opinions, in no particular order:
1) Ipod is a high-performance audio device, but keep the load 30 ohms or higher. (I have an ipod).
2) The Sony V6, Senn HD280, and Bose QC2 are all nice isolating phones. No question, the V6 and HD280 are higher fidelity at 1/3 the price. I have all three. The QC2s are nice for long trips on busses and airplanes... you'll appreciate the extra comfort as compared to earbuds, and the extra isolation and comfort as compared to V6 and and HD280. Also, any EQ you can use to decrease the bass a little or increase the treble a little in the QC2 will markedly increase the sound quality of the QC2s. But they are expensive... I'd only buy them if your budget and disposable income make it practical and you will use them very frequently for their intended purpose (decent upper-mid-fi sound, superb comfort and world-class active noise cancellation). Buy them at a Bose store and the return policy is no questions asked for 90 days (or it was when I got mine), and they will replace a pair on-the-spot if they break within a year or sometimes even later (I had a pair replaced on the spot at a Bose store, and was told they had improved the construction design since I got mine). The sound quality is sufficient to really enjoy the music if you are non-obsessive about it. I find the HD280 too uncomfortable for long-term use, but I do like the sound and it's pretty accurate (as is the V6), IMHO. The QC2s will also help preserve your hearing: I find I can hear the music well at moderate volumes even with the loud roar of jet engine noise nearby. In fact, the loudness of the music with the headphones on is often much quieter than the ambient noise of the jet without the headphones on.
3) Fussing over sound quality for a bus trip or airplane trip is futile, IMHO. I never even listen in public settings except on airplanes, where I can get bored stiff. And then your ears are popping and nowhere near at their best. Sound quality should not be the first priority for such a trip. Enjoying the music in comfort should. Save your audiphile pursuits for a quiet place in the home (as I do).
4) Headroom is a snake-oil vendor. The cable and amp stuff is littered with nonsense and deception, IMHO, and they should be called to the carpet for it at every possible opportunity. It's not exactly unique to the audio industry: check out monster cable, Best Buy, Circuit City.. Headroom's frequency response graphs, value ratings and narrative sbujective descriptions of headphones are useful information though. Use those, and their nice return policy, and steer clear of the amp and cable nonsense, and you'll be okay.
5) I can't stand earbuds. The comfort and convenience are awful. I'd much rather wear my QC2s and be able to take them on and off at a moment's notice and not have my ear canals chronically sore and at risk for infection, but but if you can stand it, there's good sound quality to be had, so have at it.
6) MP3s get quite good at 192 kbps, or even lower if you are using vbr. When people say they are hearing obvious differences at these kinds of bitrates or higher I know they don't know what they are talking about, and I can discount the rest of their opinions accordingly.
7) If you get your ipod consider getting a really nice pair of open phones for listening at home or in quiet places with superb sound quality. It has a 30mw amp, IIRC... that'll drive most (but not all) headphones quite well. This is compared to 5mw for a sony discman, for example.
So what would I use on a long bus tip? No question about it, my ipod and my Bose QC2s, with the EQ either set to either the treble increase or reduced bass preset. But I'm a middle-aged man, ears past their prime, without the money worries of a younger person on a shoe-string budget.
8) WmAx is giving you the straight dope.
Good luck!!!!!
