SIY, are you able to follow a reasoning?
The main problem with the amplifier is to amplify a signal with the less possible deformation, the least amount of distortion.
What creates the distortion? It is the passage of the audio signal through the various circuits and components. Less the signal passes through circuits / components, less it is damaged.
Why there is differents buffer stage, Sonic and others? Because each one has different performances which more or less deteriorates the signal at differents levels.
Why the Sinad noise level measurement is better on the Purifi without the input buffer? Because although it is very good, it degrades performance, like any electronic circuit.
Why want to take the signal and get it over the input buffer which for the majority of us is not useful ?
I ask the question again: why do you think Purifi spent time and money making a circuit where you can bypass the input buffer ? Just for measurement performance…?
The aim of their product range is to transcribe a recording as purely as possible, if they have left this possibility ... it should not be only to make measurement scores
So you who position yourself here as a Master, do the test, measure a sinusoidal signal at 100Hz, 1 kHz, 10kHz, at different level, or what you want to measure if YOU're be able to do this ..... measure it, at least to be critical, measure the impossible and come and give us the result …
I understand that here the measurement predominates, but for once please, if you cannot measure the immeasurable, be logical…