This link http://www.suwa-koubou.jp/repair/ka_7500/ka_7500_2.html worked for my ka-9100. As mentioned in the thread just be sure to swap the position of the trimmer vr1(2k) and r1(2.7k) with r2(1.2k). Those values work great. I also swapped the 2sd2012 for a MJE15032 cause it was all I had laying around ALSO do not forget to check for bad transistors and capacitors on the kenwood amp board, I had 3 bad/blown transistors q6, q8 q12. Plus r26 was open. ALSO ALSO, you should first adjust trimmer VR2 on the amp board to achieve a balanced bias, I got about +-1.1v. Then fine tune it with vr1 from the new circuit. Don't have a distortion analyzer, but sounds great to me.