Interesting comments, I personally find the sound very good (Grado 325i and UE TripleFi10's). I was enjoying just sitting in my chair listening to some HD music the other night, I haven't done that for ages which shows how much I'm enjoying listening to this DAP.
I've tried DSD, FLAC, and AAC and at the moment I have no complaints.
I'm afraid I've never been a fan of Sony headphones, I find their sound too analytical for some reason. The warmth I like in the sound just isn't there for me.
I did splash out for a pair of the Pioneer SE-CH5BL-K (so I could use the balanced connection) and I will admit that at the moment I can't live with the EQ off, the sound is a bit to sharp in the treble and the bass is not quite as forceful as I would like, however they are new so I'll see what they are like after a few hours of use. I could live with them as a travelling set for example. Not so expensive that if they got damaged I would be distraught!
Everyone's ears are different though so if you don't like it, return it quick my friend.
Just as a little side story, last year I was visiting John Lewis in London and they had some Sony DAP's on display (due to almost no sales they don't sell them now). So out of curiosity I plugged in my SoundMagic E10C earphones (my cheapish everyday earphones) and played a few tracks. I was very disappointed. The sound was thin, no bass, treble was very sharp (almost painful) and I was almost relieved to go back to the comfort of my iPod Classic! lol.
So I was slightly nervous of getting the 300R, the reviews had all been good (although I think What Hifi found the sound slightly too relaxed for them) but I wanted to see if I could improve my listening out on the move, and I'm glad I did
I'm not a die-hard enthusiast and I don't use separate DAC's and Amps but for me it was a great purchase and I'm very happy with it so far.
Perhaps my only gripe is I would like the build quality to be slightly better, maybe a gorilla glass front rather than plastic for example. I keep reading about the headphone sockets but I'm just being careful at the moment.
I've got about 9 hours playback on a full charge so I'm more or less happy with that but of course it's nothing compared to the two or three days of solid play I used to get out of the iPod Classic.
I'm still going to keep my iPod updated with my collection though, my car head unit has full iPod control and being able to control everything via the screen is frankly much safer.