Yeah, I've played music through my N810 on the monitors down at the studio and the hiss is definitely quite noticeable. Although the overall sound quality of the audio on the N810 is actually surprisingly good, even with super high-end equipment, if you're willing to over look that. A good work around is to keep the N810 volume low and amp the volume elsewhere with your equipment (assuming you have low S/N as well, of course ).

I'm very anxious to hear about the N900's sound quality...