I have had a Future Sound Systems TG-4 VCA in my rack for a while now and enjoy the crunchy tones you can get with it.
It has two parameters for tone, DIRT and DRIVE.
Sorry for the quick cropped picture.
Here is the VCA with no drive or dirt:
Here is the dirt turned up with no drive. You can see the signal is asymetrically squished.
The drive is a pretty hard clipped sound. This is drive at half without dirt.
Here is full drive no dirt
Finally here is dirt and drive engaged