I own the latest A-series walkman (A826) and I have to say it's the best sounding
bass of all portable players! Sound quality is superb, even with no EQ. But again, what most impresses me is the quality of the bass compared to other players. It's just much more powerful, deep, visceral! You know it's a good amp because it can deliver that much energy without effort, because bass frequencies are the most energy demanding. You have to have a very good amplifier to be able to drive bass frequencies that easily.
Anyway, besides that, the overall quality is excellent. You have useful sound improvements like the DSEE (which is great for low bitrate material), Clear Bass (the best "bass boost" that I know of, it adds a certain quality to the bass, seems more articulate, distinctive, unlike many other brands which simply put more gain in the lower frequencies like an eq boost, the sony Clear Bass seems to have a more complex algorithm behind it, making a more natural sounding boost) and Clear Stereo, there's never distortion because the player limits the volume so no distortion is ever heard, two customizable eq presets (very useful).
Treble and mids are very balanced, very detailed, and that BASS, oh that bass
Compared it with ipods (real mediocre sound) and creative zen x-fi, and heard quite a big difference. Haven't heard the cowon nor the sansa models, but I truly believe the sony model is superior in sound quality overall! Even my 5 year-old sony discman sounds better than the latest ipod
haha. Honest!