I am an electro/mechanical/acoustic engineer, a professor at a major university, and a technical fellow at a major aircraft company. I was blown away by the design and functionality of the 75i. The sound engineering is really good, not only keeping the intensity down even at 'Turbo', but designing the spectrum to be soothing at all fan settings. It is really easy to read performance, change settings, and change filters. Oh, yeah, and it does a wonderful job of cleaning the air. And it is pretty.