1.Additional resistor of 10kohms just a balancing phase splitter! The entire phase splitter is actually released and published by PHILIPS earlys '60s of the last century as the last one was made with electronic tubes.A question and a comment:
1. Why is the phase splitter unbalanced by 150k in the cathode and 160k in the anode?
2. With perhaps quite a low anode voltage on the first triode, will grid current be a problem at mid volume levels where the volume pot has significant output impedance? Have you tested for how distortion changes with volume pot position?
Simple and relatively cheap stereo integrated ****************
There is something curious going on here.Max output with a swing of 24V out of the phase splitter means Va=10V on U6 at ½mA.How do you do that with an ECC83 ? Grid current ?