I HIGHLY disagree with the recommendation of Bose ANYTHING.
Bose in my opinion have always been a company considerably more focused on marketing and lifestyle equipment than audio of any kind.
The Grado's would be my choice, but depending on what kind of iPod you have, you'll find they're going to WAY outmatch the iPod itself. The Analogue outputs on the current classics are way sub par, and even units with good analogue outputs, like the Creative Zen Vision:M that I used to own, the limitations of the small package are readily evident even when listening through Grado's SR60s, which while great in their own right are a good ways behind the RS2is.
Bear in mind your usage too. If yougo for open style headphones like the Grados, you'll get ambient noise creeping in and will want to be in a quiet place to listen. How feasible that is in the middle of a tour in Iraq I don't know. The same flaw is evident with the sennheisers.
If you want really great sound with great ambient noise reduction, I would recommend looking into some good earbuds, particularly those available with custom tips, like the Etymotic ones, or Ultimate Ears. (Disadvantage - You'll need to have an ear impression taken to get the truly custom ones. If thats impossible, you can still get a great, high quality replacement tip to suit you from a company called Comply who specialize in replacement tips made from a special silicon foam.)
Some of the best earbuds available are made by Shure, they sound great, they block out a lot of ambient noise and latent cable noise is low. The only disadvantage to them is that like all earbud type headphones, bass reproduction is lower than similarly priced full cover headphones, although according to all reviews of the shures I link to below, that problem is pretty much negated in their more expensive designs due to the use of seperate drivers in the earbud housing.
Check these out.
Shure - SE Products - SE530 - Sound Isolating Earphones
Etymotic Research, Inc. - Musicians Earplugs
Ultimate Ears Custom Ear Plugs - Custom Store - Ultimate Ears Earphones Headphones Personal Monitors
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