REF: [Previous post from a while back, from dieter]
 I have quickly fitted a 15k carbon resistor in place of the 22k on the
 A-120 Low pass filter and the level increase is quite handy.
 (Originally i was curious as to why the output was lower than i had
 initially expected, so this mod is great for that and spares me a vca :)
 A very basic and useful mod.