I recently purchased a like-new iMod through this forum, and it is amazing. As it burns in (along with my Hornet), my portable rig is beginning to sound distinctly clearer and more detailed than my home rig (oh, for shame!). Well, using my K701s as my portable 'phones is probably cheating (I accidentally left my KSC75s in my dorm room (which is locked over winter break) -- what else am I supposed to do?
), but regardless, the sound quality of an iMod blows away that of a 5G iPod (I haven't heard the 5.5G (is that what people are calling it?), but I severely doubt it can even approach the iMod).
As for your AV710, I can't say anything since I've never heard it. If you can afford the iMod (and are willing to use a headphone amp 100% of the time -- it's mandatory since Red Wine converts the headphone out to a high-quality lineout and the existing lineout to a simple charger / USB connect), I would highly recommend trying it out. If you don't feel it was worth it (after some decent burn-in time -- some people recommend upwards of two-hundred hours), you can likely sell it for a slight loss on these forums.
For maximum portability, I recommend either the Tomahawk (which I haven't heard, but other people can testify to its sound quality) if you listen mainly to IEMs or other low-impedence headphones or the Hornet (which I own and love) if you would like to have the option to use high impedence headphones (though probably not as high as the K1000
). I doubt you'll be disappointed if you do indeed purchase it!
Let us know how everything goes.