Hey man! Great question:

Have you tried restringing your guitar with thicker strings? For the low tuned tutorials i will use around 52-13s. They sound much tighter than trying to detune with regular strings.

Also, as far as amp settings go, try reducing the pre-amp gain, as well as the low eq. I find that even just a little less of each really helps to tighten things up.

Lemme know if any of this helps, and keep rocking!
Mike