Starting from the math or @sarumbear in one of the first posts:Because the gain is doubled, and hence any noise (internal from the amp, or coming from the source) is also doubled.
"Sound levels in a quite studio is around 20dBSPL. Loud club (disco) level is around 100dBSPL at 1m. It translates to 110dBSPL at 10cm. Assuming that is the maximum volume your system is set to you should start hearing noise from an amplifier that has a noise figure of 90dB or less. Purifi spec is 116dB SINAD, 26dB better"
So i tend to disagree, even if noise is double you add just around 6dB in the equation and the Purifi should be 20dB better than noise floor.
You shouldn't be hearing absolutely anything even with the higher gain configuration of the Audiophonics if properly designed.