I'd like to knock the price, since $450 seems like a lot for a little headphone amp/DAC, but you get what you pay for, especially in the high-end audio world. And, in my opinion, this is a great product.
I am just getting back into high-end audio, building a new kit. The first things I wanted to do were to digitize my CD collection in lossless, build a media server with direct digital out, get a really good headphone amp/DAC and good headphones.
After a long search, reading several forums, I bought the following:
Sennheiser HD650
Icon HDP
Nuforce E7
I'm mroe than happy with all 3.
For the E7, I use that as a headphone amp between my laptop or my iPod and my Grado 60's. Great portable setup. The E7 will drive my HD650's, but I prefer to keep that setup separate from my portable kit.
The Icon is my home headphone amp/DAC. I can use the digital in from my laptop to the HD650's, which sounds amazing. I can also use the analog out to connect to a small amp/speakers for a 2nd location.
Overall, I think having a separate portable and home setup is nice to have, since I don't have to move things around, and I really do prefer having the Icon wired up at home to my system. It would work fine connected to an iPod, if needed.
As far as the high-end audio stuff like "extreme cross-over, wide dispersion, ample headroom, vast soundstage", I don't feel qualified to comment. This is my first dive into this world, and I bought this setup without listening to it first, just based on the reviews I read on-line. For the sound quality, it's amazingly higher quality than headphones plugged into a laptop or A/V receiver or iPod. The difference is striking. To be honest, I wasn't planned on re-ripping all my music, but once I heard the difference with the new hardware, I had to re-do my collection in lossless. You CAN tell the difference, even with 320K MP3 files.
Again, overall, a great setup. Thanks to everyone on the forums who helped me with the decisions and spent their time posting very extensive reviews of the equipment.