Hi guys, so I have a Fender Super Reverb Reissue that I love but am needing new tubes for. I just have two quick questions. I think I know the answer to both of them but just want to make sure and check with the pros. 1) In the pic below, is the hole circled that almost resembles an input jack the designated trim pot for power tube biasing? I think so but just want to make sure before I insert a screw driver in the amp when on. 2) Also, I know I should get a match pair of 6L6gc power tubes but obviously the preamp and rectifier tubes don't have to match, right? You guys are always such a great help. I appreciate your time. As a bonus, if you have any tube recommendations for a SRRI, I'd love to hear it. Are modern tubes really that bad or should I limit to only NOS? thanks!