I imagine that at least some of you have used the Tubes4HiFi VTA70 board in your ST-70. In examining the VTA70 input circuit I see that a 270k ohm resistor is used as grid leak resistor along with a series 10k ohm ahead of that at the input jack. I am using my venerable PAS-3X preamp to drive my ST-70 which currently is operating with 6GH8A driver and phase inverter stages. The combination works quite well.
I am wondering about the difference in the input impedance of the 470k ohm grid leak resistor versus the 270k grid leak resistor used in the VTA70. Will there be a mismatch between the PAS-3X and the ST-70 if I change to the VTA70 board? If so are there recommended changes to the PAS to compensate?
Joe