I bought this MP3 player to replace my Cowon D20 which broke out of the blue. I use this MP3 with 32Gb Class 10 Micro SD card from Sandisk formatted to NTFS. Player is so much bigger than D20 but it fits well in hand, button layout make it simple to ...Read moreswitch songs and play/pause on the go having player in my pocket. I have used it for last 3 weeks and must admit it is very sophisticated piece of kit. It does have a feature to delete a song or the whole folder from SD card - convenient if you are cherry picking songs from the albums. It does have line out - I run my Roverbeats BT speaker via AUX though this output and sound is loud and powerful yet I can apply EQ (someone reported that EQ is no applicable when playing through line out, but that wasn't my case). Sound... Comparing to Cowon sound is unbelievable - I can follow specific instrument line if I wish, I can hear lyrics better as they are clearer, I can hear music as it was intended. In other words I would say - listening to this player is like listening to known tunes via studio monitor speakers, you'd be surprised of sound. But mind you - this player shows its best if you pair it with cans for £100+, I wasn't that impressed when listening to it through Senn CX400. You also have an option of switching gain from low to high - this is to drive higher impedance headphones. EQ - at first I was a bit disappointed as turning EQ on was bringing volume down but then I learned that this is due to a headroom of 6db that is being enabled so you can use EQ at highest setting without clipping the signal. EQ is great - powerful bass but at the same time not overpowering; there is clear separation - here is bass and there is the rest of sound stage; there is clear treble but I found that treble might be lacking a bit if your ears are used to sound of Cowon. Also, some listeners do prefer to leave EQ off - possibly due to studio monitor effect I described earlier. UI - takes time to get used but is very intuitive. One thing I have come across - sometimes switching songs can be laggy unless you add songs to a playlist and play them from there. Also, should you delete last song in folder player won't play first song from next folder - I got in touch with FiiO about this and they responded that this is due to firmware design and not possible to fix, I was advised to use playlists and deleting songs from there (when you delete song from playlist it is also erased from SD card). FiiO support was also surprisingly responsive and helpful. Playlists - this player does support external playlists, you can create them in foobar2000 or WinAMP but with one exception - song path must be less or equal 128 characters. Apparently this is due to firmware/playback design and is not planned to be fixed any time soon. Battery - it is advertised to be 11h playback and 4h charging if from wall socket. In real world I get 8h of playback and 4h charge. This player has very nice feature to go to sleep if paused and then left without attention for 5mins. Possibly due to sleep function I am getting less playback time than advertised. Overall - I am very glad that I switched from Cowon to FiiO. Special thanks to Colin from AMP3 for advice and suggestions.