1. Thats a lot of variables - do you really think any single board member can test all of this, and with hearing that lines up with yours ?
2. I have listened to FLAC and 320K MP3s on my Cowon, and Apple Lossless on a 4G Nano. Per my earlier post, I returned the Nano for a refund within 24 hours. Draw your own conclusions, but I love the Cowon's SQ.
3. I dont have the X-series, but my S720 series Sony is fantastic - not as good as the Cowon for SQ, but better as a genuinely portable player with a good user interface.
4. I consider my Sony IEMs to be markedly better than the 485s, a fairly mediocre set of headphones (I have owned mine for over 2 years, but no longer use them), despite costing about half as much.
My advice is that you need to listen to the Sony and the Cowon, and get some new phones - MS1s if you can afford them, Koss KSC-75 if not.