The following changes and improvements have been made to FW2.0 compared to FW1.6:
1. Added library search function: activate by holding Shortcuts button in any category or folder browsing screen; use previous / next buttons to switch between numbers and alphabet);
2. Added option to manually clear media library database file (via System Settings);
3. Added option to delete a track (outside of Now Playing);
4. Added play mode: play single track and stop;
5. Added Line Output level options (fixed or variable level);
6. Added DoP and D2P options to S/PDIF output;
7. Added DAC output reconstruction lowpass filter options (steep and gentle slope);
8. Added Recently Played playlist (via Play by Category);
9. Added support for ReplayGain;
10. Added docking support to use with FiiO K5 or DK1;
11. Optimized UI operation and speed;
12. Amended the EQ setting to be dynamic, so as to avoid a sudden low voice when turning on the EQ or a sudden loud voice when turning off the EQ
13. Fixed issue with hidden files stored by a Mac OS computer accessing the cards on the X3 2nd gen;
14. Miscellaneous bug fixes;
credit : http://fiio.me/forum.php?mod=viewthread&tid=41365&extra=page%3D1