Re the voltage settings, unlike some other posters , I found a huge difference. My system is a rouge Sphinx
In my still limited experience the voltage settings do indeed make a difference.
But since I connect to different sources regularly I have so far not come to the conclusion that there is one ideal setting that works in my system.
With Qutest directly to my pream/amp and speaker at 1V with downloads I have to raise my volume to roughly12 o'clock with most recordings and get a slightly lower noise floor using the same setting with my main headphone amp and downloads.
At 3V I get a wee bit higher noise/hiss and sometimes overload issues.
The hiss is most noticable via headphones.
Am I correct in guessing the higher gain setting from Qutest's output stage is causing hiss/noise to rise?
I can play at the same dB loudness level with less hiss with the 1V setting and my headphone amp has 4 dB better snr than Qutest on paper if I interpret things correctly.
As far as common mains noise is concerned my Benchmark headphone amp lists below 140dB.
Quite an impressive figure.
But I can't find any similar measurement for Qutest.
With my main speaker based system hiss is not a problem really,since I never listen with my ears close to the electrostatic panels but from a distance of at least 4-5 metres away.
I am happy that the settings are there. But I wish they just like the filters, had been adjustable via a remote.