I'm no stinking "expert" but I'm just curious of concept where an amp has to hiss to deliver power. Poorly implemented dac/amp have circults or low grade components that introduce noise, or are receptive to interference, and noise creep in during the amplification, and thus the higher the gain, the more this noise is amplified. But if the upstream (save for any background noise inherent in the recording), there is no noise to be amplified then regardless of the power output, their won't be hissing.
In any case, I have dac/amp/dap that hiss, I have those that don't. And I'm sharing my first hand experiences and not (il)logical conjectures. And it is that Hugo does drive my hd800 (other other's) well and don't hiss with IEMs that are regarded to be most sensitive and most intolerant of hiss. And yes Roxanne universal that I demo don't hiss also. Of course everyone is free to believe what he/she believes.
Edited by kkcc - 6/25/14 at 7:16pm