In this thread (https://www.tdpri.com/threads/preamp-signal-through-my-rr800v.1032352/) it became clear that I've only seen fully bypassed gain stage load lines. I'm trying to update my scripts for unbypassed gain stages. I'm currently using https://worldradiohistory.com/Archive-Rider/BOOKS/Inside-the-Vacuum-Tube-Rider-1945.pdf (p327 and futher). The first baby steps have been taken. I'll try to give updates. As this is the first time I'm reading/doing this, any feedback from you guys that actually know this stuff is very welcome. Sneak preview: Lower left lines are an error. I need to find a reasonable starting point for my fminsearch.