George is omitting the rest of Nelson's comments when he makes that quote. He seems to do this as part of his 'product protection' program, since he sells (actually a very good, but also obviously not of his own design) passive volume control. Here is the rest of that passage, starting at exactly the point that George stopped:
I
suppose if I had to floor the accelerator to drive 55 mph, maybe
I’d think the life was being sucked out of my driving. Then
again, maybe I like 55. Nice and safe, good gas mileage…
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.