Want to share some measurements of a few Stax. These were measured by oratory1990 on an industry-standard GRAS 43AG rig. All but the 009S were my personal units.
SR-007A (2018 aka MK2.9 version) - with blue-tack mod
My personal favorite without EQ was the 007 MK1, but the 009 with EQ is my favorite overall. They all become more similar than different with EQ, of course. Plus the 009 ergonomics agree more with my head
More here: https://www.reddit.com/r/oratory1990/wiki/index/list_of_presets