Nano as travel piece

I've been using Sennheiser CX-300 in-ear phones with my 2nd gen ipod Shuffle and they sound great. Easy to drive so they give good battery life from my ipod. They block outside noise fairly well but not as well as my over-the-ear Sony noise-cancelling 'phones so I still use the Sony's on the plane.

Most of my music is loaded at 256kbs due to the limited storage space anyway so they easily resolve all the detail available in those files. I've listened to them on lossless files ripped from CD to my Mac mini and with my NAD Monitor Series model 5000 Cd player's headphone jack and they sound even better then. Easily worth the $70 or so I paid for them two years ago.

Westone Om2, Om3x, Om1. Excellent at their price points. Natural treble, midrange promient, and on the 2 & 3 bass is featured.

Those are the "professional" models. The "consumer" models are a little bit less transparent and less linear. The Westone 3 is VERY bass heavy. Models 1 & 2 are newest and I've not experienced them.

Westones are known for being VERY comfortable for in-ear phones.

Several years ago I went to a "head-fi" conference and tried all the brands earphones. Westones were the most natural sounding and most comfortable too. Shures came in second, IMHO. Etymonic were a bit lean and detailed - solid state sound, if you will, but I know they have raving fans just like Westone does.

Once you learn to use them - get the right fit for an ear piece and learn to install them properly and get used to them - it is staggering how great sound quality you can get for the price of a medium quality pair of audiophile interconnects.

Art

I use Etymotic ER-4P with my iPod Touch and they work well, the only issue is the bass is a little challenged. If you have the ER-4S then you may need an amp to drive them. There are a lot more in ear headphones available now (compared to when I got the ER-4Ps), none of which I've heard. I would suspect an over the ear headphone will require even more power than the ER-4P (or other in ear) so you may have serious degradation. I chose the ER-4P since they are so small, over the ear headphones are just too bulky for travel. I also don't know if the Nano has the same headphone driving capabilities as the Touch.