Take a look, below are 3 scope images using different cables to feed signal into the tuner converter control grid (Test Point A). Note I had to turn down the vertical scope by one setting for the direct connection cable as the signal came in stronger. I tried to overlay all three images in photoshop, each was slightly different in horizontal or vertical size but I would have to argue the curve and marker locations and marker attenuations all look very close.
Maybe antidotal but while waiting for the set to warm up I was watching some content via the converter box and the picture to me looked better, so at least I am not making it worse.