I have the SR225i. I do prefer the sound coming out of my ODAC/Little Dot I+ over my Samsung Note 2 phone for critical listening. But for moving around the house, I'm not listening nearly as closely, and the SQ of the Samsung is good enough for me. It also seems that the SR225i really just do sound good with a multitude of sources. I have Ultrasone HFI-780 that respond more dramatically to being amplified, where I have more of a sense of loss when they are not amped.
However, I did just order an O2 headphone amp to go with my ODAC and the Note 2 (Note 2 has USB audio out). Not for my pocket for moving around (the O2 is a little big for that), but so I can sit anywhere in my house and relax with some critical listening, or if I want to use my headphones with my laptop in another room to get away from my computer workstation in my home office. Probably will take it on business trips for relaxing in the hotel room at the end of the day.
I had the same sense w/ my Ipod w/ more causal listening it sounds pretty good. Hey, I took a look at their website, that O2 looks pretty sweet. Do you consider that an upgrade from your Fiio E17-or will you use them for different applictions?
Edited by markm1 - 2/4/13 at 1:00pm