Being a gadget freak I've been lucky enough to have opportunity to try a number of different MP3 Players. Some stand alone players, portable media devices and mobile phones with players build in.
The three that stand out for me is the iPod 30 GB Classic (Fifth Generation), the Sony W810 phone / walkman and the Blackberry Bold 9000. All for different reasons.
For consistency, I have loaded the same MP3s on each player as well ensuring I tried each player with the same headphones. The headphones I used were a pair of AKG DJ K518, they are relatively clear, nicely balanced and a have a fair bit of punchy compared to some other headphones I have used.
I have to say I was quite surprised with the results, but in saying that everybody is different in terms of how they like to listen to their music. For me the iPod had the poorest sound quality with the music sounding distorted and muffled at times. I turned the graphic equaliser off to see if this improved the sound quality which it did slightly but not enough it to say it fixed it. Turning off the equalizer also removed some depth in the sound and left the sound less amplified and lack that richness to enjoy it.
Next I would say the sound quality of the Sony W810 was quite rich and crisp overall, the only down side of this device was the lack of a 3.5 mm jack outlet with a Sony converter lead needed, however this had no impact the sound quality (expect possibly the lead having to be that little bit longer). I would say that W810 had the widest sound range of the three devices with high highs and bassy lows, but I felt it struggled a little in the mids a bit.
While I am known for being a Blackberry fan, I have to say that I was mostly surprised and impressed with the Blackberry Bold 9000's sound quality. While RIM are known for not placing a high focus on their built in media player, the sound was clear and crisp and easy to listen to for long periods. Music didn't sound muffled or distorted at any point, even at relatively high volumes. I also felt that the output was nicely balanced with no excessive high screeches or deep lows.