While I expect that the n900 only has a 16 bit DAC, I've been quite pleased with the sound quality it gives with my Sennheiser HD515s. Based on my lossless (compared to the source) CD rips and listening to my symphony on the device, I'm happy to say that I don't notice any of the notes getting lost or muddied, and I actually have to turn the volume down for comfortable listening. That hasn't been my experience with some other mp3 players, though I'm sure there are dedicated portable audio players that can match/best the n900.