Come on rick, there's not that much talk just about the little Xinfeed PLUG
But well, I have one, and it is nice to have. The provided crossfeed is just as good & subtle as with Xin's amps, and it also adds a tiny little bit of resistance (I think 10Ohm?) so it may even enhance the sound of certain cans.
Now for the trouble: It is incredibly ugly. Much more ugly than you would think from the pictures. It also looks as though it would fall to pieces at any moment. Of course it does not, since it is a handmade quality item. The real problem I have with it is more basic: It sticks out from my iPod's headphone jack, and I am always afraid of harming the jack due to the big fat lever the adaptor represents. A little inconvenient & a little dangerous.
In fact I plan to approach Xin, who right now should be up to his ears in supermacro/micro/mini related issues, and RnB180 about releasing a new version in cooperation i they feel like it. I think it would be much more convenient for all kinds of portable sources to have a superflat angled jack (as you have with Etys) with a small run of very flexible high quality cable that is terminated into the Xinfeed adaptor, the whole thing say 4-5" total in lenght. So in short, a Xinfeed "dongle" instead of a stick-out adaptor.
Nevertheless, I heartly recomment the adaptor as it is, one of the best valued upgrades you can give to your ultraportable setup, and of course the *only* possiblity to get ampless portable crossfeed.