Quote from
@FractalAudio
"One common theme with new users is the "blanket over the sound" complaint. Often this is due to excessive Master Volume values.
The Master Volume behaves just like the actual amps. However, unlike an actual amp, if you put it on 5.0 it won't cause your cat to hide for several days. This can cause the user to set the value too high as the physical feedback of painfully loud sound is not present.
As you turn up the Master Volume many amps get darker and the bass gets mushy. The key is to find the sweet spot."
So usually dull, or the "blanket over the sound", relates to too much bass and/or too high master amp volume. Some presets have the volume on 10. I find reducing it until I find a sweet spot cleans up the tone. These days, because my setup is a little different, using a tube power amp and guitar cab, I find my sweet spot on the volume, then find a good gain level without turning the gain up so high it muffles everything. I adjust my bass usually lower than the default.