Hey, look at all the people here - that's better!

I agree with everyone above regarding the precious iPod and its many bastard cousins - frankly, they all sound pretty bad to my ears. Of course, that's only when listening through nice studio headphones in a quiet environment - add a noisy toddler or two, and frankly, they sound decent.

As far as flat v. non-flat frequency response, it all depends on what you're measuring, or (more critically), whether you're measuring at all. I've been doing recordings for about a dozen years (mostly classical music - also lots of electroacoustics), and I have never had a listener key in on "non-flat frequency response" as a problem with a recording. Yes, it's a nice way to measure electronics (and even better, to market them), but it has very little to do with how we listen. Besides, there are too many other variables - non-linearities in the amplifier stage(s), different transducers (speakers/headphones), different listening environments, and the hearing of the listener. Not to mention the listener's preferences, mood, etc...

Okay, I'm drifting WAY off topic. Sorry...

As far as listening to binaural recordings while on the move, check out the Etymotic ER-4B in-ear headphones <http://www.etymotic.com/ephp/er4.aspx>. The 4B model is specifically designed to reproduce binaural recordings, and they all have excellent sound isolation characteristics (in case your listening environment is less than ideal) - typically 35-40 dB isolation. Price is about $250-300, and you'll certainly have to order the 4B, as stores tend to focus on the 4P.

As far as UPnP, I'm leaning toward a dedicated NAS device with all my media on it, and with the option (?) of using the N810 as a remote of some sort. This is well beyond my areas of expertise, and as I said, I only started looking at it yesterday, so I don't have much to add just yet. Maybe in a few weeks.

Perhaps Canola could be used as a UPnP source/controller?