I am sorry but I do not understand what you mean by "dryness"?
The VH4 is a tighter feeling amp. By this I mean that it does not have any "sag: or "give" to it when playing, such as a Marshall or Fender might have in feeling.
The actual tone of the third channel of the VH4 is what everyone that plays the amp raves about, more then any other thing about it. It does not feel or sound dry, in that you can hear the sweet crunchiness of the tone.
The Herbert does not have the same feeling. It is not quite as tight feeling as the VH4. The notes come out feeling not as direct sounding and stiff and immediate.
However the tones on the Herbert are every bit as sweet and crunchy, dweety, and juicy. Because the Herbert has more wattage, the thrust of the notes coming out can make the sound feel more powerful if that is what you desire, but they don't have to come out feeling that way. It depends on how you set up the amp. You can get clarity in the distortion on any Diezel. While playing at a bedroom level volume, if you simply turn up the global or channel volume, you can hear the distortion start to clear up as the volume increases. If it sounds too clear to you, simply add more gain to the setting. The Diezel amps lack a fizzy, buzzy sounding thin top end. The overall character of these amps is more hefty, and meaty sounding, although by judicious use of the EQ and mid-shift controls, you can make the Herbert sound as big or thin as you desire.
I hope this helps to clarify a bit for you.
Stephen