I checked, OV4 does not work properly with 2 tube amp. It detects fault and disables BIAS.

Propably "true" OV2 is EOL, and OV4 with 2 adapters is replacement of OV2.

Yes, I know about OV2 but OV4 is, in my opinion, more versatile. Does anyone know how this equipment regulate bias. How OV4 affects the bias of the tube?

Hi, can I use OV4 with amplifier which has 2 tubes at output stage only.