Any! active stage/s introduces noise hum and distortions, increase their gain and you increase those as well.
This statement is still false.
So it’s best to use as "most" as you can from the "passive" Master
volume (which has virtually no noise hum or distortions), and use as
little as possible "gain" from the active stage. Couldn’t be simpler.
Perhaps. At least it could make sense. The above comment does not. What were you trying to say?
Nelson Pass:
" A “passive preamp” - just an input selector and a volume control.What
could be better? Hardly any noise or distortion added by these simple
passive parts. No feedback, no worrying about what type of capacitors –
just musical perfection."
You cherry picked that one... What could be better? Nelson answers that:
Is impedance matching an issue? Passive volume controls do have to
make a trade-off between input impedance and output impedance. If the
input impedance is high, making the input to the volume control easy for
the source to drive, then the output impedance is also high, possibly
creating difficulty with the input impedance of the power amplifier. And
vice versa: If your amplifier prefers low source impedance, then your
signal source might have to look at low impedance in the volume control.
This suggests the possibility of using a high quality buffer in
conjunction with a volume control. A buffer is still an active circuit
using tubes or transistors, but it has no voltage gain – it only
interposes itself to make a low impedance into a high impedance, or vice
versa. If you put a buffer in front of a volume control, the control’s
low impedance looks like high impedance.
If you put a buffer after a volume control, it makes the output
impedance much lower. You can put buffers before and after a volume
control if you want.
He confirms what I have maintained- a buffer at the input and a buffer at the output of the control are both helpful.