I guess the title says it all. This inexpensive little application ($29) quickly analyzes and graphs plugins for frequency response, harmonic and intermodulation distortion, efficiency (how many samples it can process per second), has an oscilloscope, and measures compression. You can compare two plugins at once, or one at a time. It's very fast. The graphing is instantaneous once you load a plugin and select what you want to measure. Think two models of an API 2500 compressor in plugin form do the same thing and have the same harmonic content or frequency response? Not the ones I measured!. Same with console emulations, EQs, amp models, etc. There are differences between models that explain why some work better on certain sources than others, or perhaps why you might like the sound of one over the other. I find using this tool fascinating. The graphs tell you why you're hearing what you're hearing, and are helpful when you're thinking about what you want to accomplish in terms of frequency response, distortion, harmonic content, and so on. Even phase alignment. It will also measure hardware. I haven't tried that yet. So, yes, a handy little tool that doesn't cost much. PS - it does require some basic audio experience to know what you're supposed to be looking for, but there's so much info on the web about all of these measurement terms that I think anyone can buy the tool, and with a little research, understand what's happening.