This is also why testing should be done after a device is made. Programs and simulators are a necessity for design work. As is the importance of measuring after the build to confirm the intent. Lastly, personal listening is necessary because as you can see with speakers for example. Various manufacturers all produce a speaker with a flat line or performance similar to others. Yet the sounds are different.
There are a lot of things that measurements do not expose, and still, we hear something different.

Bill