Your general opinion of this product.
I could not get the tone I wanted from my Marshall combo amp at church. Then I started reading about bass amp coupling, where the sub-frequencies get absorbed by the floor in some settings like a hollow stage. Bought the GRAMMA, slipped it under my amp, and WOW! My amp sounds like it should. Stop fiddling with knobs and changing strings, your problem is not your gear, it is the floor!