I didn't hear much in any of the clips either
- But I still hear it sitting here playing in front of the FRCabs, though less than before now using mono delay - so my best guess now is that what I'm hearing is reflections from my own room that would not be picked up by the mic I used in clips 2/3 above as it is not sensitive to anything more than a foot or two away. Also these different cab types I have are facing in different directions around me, and are at varying heights so the room reflections answer would fit. I've tried treating my assigned mancave corner with cheap foam absorbers but I'm not sure they are doing much to combat some largish aluminim ducts passing above.
Anyway, I'm going with that for now - thanks all for the feedback throughout this adventure.