I have an NAD T762 which is combining the Tuner and CD (and a few others) at the Audio input selector IC U301. When the volume is changed, the left channel is killed by the same input selector IC U301 TC9273F-004. Vcc + and - 12 is nice and clean along with the clock and data lines coming into it. I thought it unlikely that both (U304) selectors would be bad in the exact same way so I exchanged them with the same results. I believe there is somthing wrong with the 9273_DATA line but it looks good on the scope when functions are changed. That leaves me with the data itself being corrupt or invalid from U209/U201 on the front panel. I believe U209 lets 6 different data sources talk to 2 ports on the main micro, P3.4/DO and P3.5/T1 pins 16 and 17. Can anyone help isolate this problem down a little further? With 6 different sources as oportunities for a problem, my head starts to spin a little.