I tried the mod following the 2 schematics you kindly posted, and after doing the mod it sounds like a fart.
I've had to put a 3 way switch instead a 2 way (on-off-on). The off center position I didn't know what to expect, but sounds a lot like my SD1, all the bass frequencies are gone and there's less gain.
All the caps are metal film, and the one that should be Silver mica it's a ceramic one , but I don't think this is the cause.
The two "on" positions; very noticeable volume drop, incredibly fuzzy sounding (in the same way that a tube amb sound when the bias is not correct).
I changed all the caps and resistor and apparently everything is OK, I gues it must be in the clipping diodes.
HELP !!!!!!!! :cry: