AR Ref 300 Vs 300 Mark II Sonic differences...

The reliability of the MK II is vastly improved.

I would take the 6922 input any day. And remove the Sovtek tube, throw it in the trash and try out any number of tubes such as the Telefunken, Amperex PQ, Valvo, etc.

AR stands for Acoustic Research. You must mean ARC.

Besides using J-FET drivers power supply regulation is also improved.

I'm not aware of an Audio Research MKII that isn't a genuine improvement.

Just found some info and it confirms the MKII uses the solid state j-fet input. The original uses the 6922 tube as the input driver. Did anyone ever compare the two?

Thanks and Aloha