I think it is best to measure across both emitter resistors, this allows you to take into account any offset voltage. Any offset in voltage will create a small imbalance in your measurements.
80mA is on the high side, it allows for a larger class "A" region and lower THD but it makes the HS/bjts run much warmer at idle. Since the original STK-0050 has no adj for bias, I am not sure what one actually reads in a SX-780, but I assume it is around 32mA.
I doubt that you will hear any difference in sound quality with the higher bias.
Once you pass the DBT test, you are good to go, you can take it off the DBT, then adjust the bias/offset. Do not adjust bias on the DBT as it will be incorrect. Also allow the unit to warm up to thermal stability, then check/adjust bias for the final time,
80mA is on the high side, it allows for a larger class "A" region and lower THD but it makes the HS/bjts run much warmer at idle. Since the original STK-0050 has no adj for bias, I am not sure what one actually reads in a SX-780, but I assume it is around 32mA.
I doubt that you will hear any difference in sound quality with the higher bias.
Once you pass the DBT test, you are good to go, you can take it off the DBT, then adjust the bias/offset. Do not adjust bias on the DBT as it will be incorrect. Also allow the unit to warm up to thermal stability, then check/adjust bias for the final time,