Well now that I'm back home, i can do a better comparison of the nano sound quality with the range of phones that I own and use. Not a comprehensive list but my wallet is not either.
Also this is based strictly on my probably flawed ears with my music all in 192kb AAC ripped on a Mac. Music consisting of Bloc Party Silent Alarm, Miles Davis Sketches of Spain (remastered), Philip Glass and Brian Eno Low Symphony, Emmylou Harris Elite Hotel, loading all the same files on all machines
No testing instruments
I have currently:
60GB ipod photo (when they still called them photo)
Blue 6gb ipod mini (second gen)
Silver 4gb ipod mini (first gen) (now my neices)
Ipod Shuffle 1GB (girlfriends)
Nano 4gb
Sony Ex71
Shure E4c
Super Fi 5 pro
Apple Earbuds (my running, i don't give a damn if they get broke, freebies)
And the winner is........ well it depends
The only clear loser was the original ipod mini. It did not sound the best with any of the phones having the weakest bass.
The sony 71's are definitely a distant third in headphone sound though a bit better than the apple ear buds (except for cable noise when running) and not as awful as I remembered after getting my shures
To my ears, it's a virtual tie between the shuffle and the nano with the shure phones, and I would give a very slight edge to the nano over the shuffle when used with the superfis which just had the most pleasing sound to my ears (only way to describe it), but only by the slimmest of margins.
The photo definitely sounded best by a long shot with the super fi's though still back from the nano or shuffle. The shure's had weak bass with the photo as many have described here. And by the way, my photo does not seem to have the distortion problem that some have reported on.
The 2nd gen mini was a consistent 4th regardless of the phones.
This is as far as I intend to go in testing this out because I find if i don't i'll get obsessive about it and lose sight that the reason I have these things is to enjoy my music. I cant tell you the number of times i ripped, then re-ripped, then ripped yet again when I got hung up in bit rate and mp3 versus AAC crap.
So ones person's very un-scientific opinion.....