First of all, I would like to emphasize that I am not an API user. Despite this, I got the chance to use Volko Audio's QA series EQ software recently. Here is my evaluation:
The interface is designed by plain visuals that could be understood clearly on the computer screen. The interface of the software does not resemble the appearance of the original hardware. This makes it easier for the user to perceive it visually. That is, a button that we translate virtually with a mouse, graphically indicating the distance traveled by the button, and leaving the button as a graphical trail. Usually in such modelling software, to see what is happening at the interface (especially on small buttons), we need to lean onto the computer screen. What I liked most regarding the interface is the positive value that this software has contributed to audio and music. Even if you don't buy, you should absolutely try and decide for yourself. It has no downside to the quality products I have used so far in this area. I say, you should absolutely try it.