Thanks for your answer, Sotiris. According to Westone, the Westone 2 is rated at "Sensitivity: 117 dB SPL/mW @1kHz" and "Impedance: 33 ohms @1kHz", which mean nothing to me
. I've never noticed any hiss using mine with my laptop, my now dead Sony NW-HD 5, or my girlfriend's Sony NWZ-A818, and I've excellent hearing (at least in the sense of picking up ambient noise while not listening to music; that is, I can hear the dog barking next door despite the closed windows and the running air conditioner). What's your overall opinion of the RoCoo P, not just sound quality but also UI, build quality, etc.?