I've been using an Iriver IHP-140 since 2004. Back then it was the only alternative to the Ipod. In reviews they actually
praised the Iriver to be the best sounding MP3 player.

So it's 2011 now and I STILL use my Iriver IHP-140 (with Rockbox firmware). A couple of days ago I ordered a Cowon J3 which is
- according to reviews - supposed to be one of the current best sounding mp3 players...better than the Ipod Classic or Ipod Touch.
Well....I received it and did some extensive testing. Of course I was curious and compared the sound of the Cowon with the
Iriver (neutral setting, 320 kbps track, Sennheiser PX200 headphones). To my surprise the Cowon didn't sound as good.
There are some bass frequencies which you can hear with the Iriver but not with the Cowon. Apart from that there's another
difference ...well...the Iriver sounds warmer...more dynamic. The Cowon J3 sounds more aggressive...less dynamic.
So to my ears the reference player of 2004 still sounds better...I might return the Cowon.