Modifying Amplifier feedback circuit

[reddish75]

I have a Kenwood Ka-1000 amplifier with Sigma Drive that I'm repairing and have been told that the feedback circuit running through a switch (S6) on this amp is a weak point, same person said that the feedback circuit can be reworked to follow the best implementation of this from another amplifier with similar topology the Kenwood L-02. This is slightly above my understanding as I would also need to ensure that I have some dc for the Ka-1000's tone controls, any help, tips or pointers? Attached relevant schematics, ka-1000 first.

[rcbuck]

You may get more help with this at DIY Audio Forum.

https://www.diyaudio.com/forums/index.php