Just got an Origin 20H, and I am trying to figure out which of the preamp slots are v1, 2 & 3? Wasn't sure how they are ordered if anyone can help. Is the one on the far left 1 or 3? From what I've read, the v1 is a JJ? Looking to change the 2&3. I have Sovtek 12AX7WA in my parts drawer , didn't know if that would be a good option for 2 or 3. I'm not that well versed in these things, so pardon my ignorance. Thx!