Bass renesoance is cheaper than a sophisticated cabinet design that is going to cost you many many euros.. Why do you think that many people drilled holes in the back of the PC 350 and perceived a noticeable amount of bass has been added? O let me guess that's all in thier heads??? Literally? Lmao. Go buy your self a non ported sub and let me know how much you like it or how much money you spend on it and how it doesn't sound much better than a ported one to begin with. It is just cheaper and easier to port a cabinet than it is to specifically design a cabinet that is going to produce the perfect amount of bass. Not saying that sealed cabinets or closed back designs suck, they are in fact better, its just that the good ones are very expensive for the little amount of quality gain that they offer. The 350's closed back was not engineered for the most perfect bass response, i personally like it and think the bass is just right where others think that it is weak. But for bassheads what they should be after is the opened eared design because it is essentially a bass port, that can be backed up by many people on the web claiming that the 360 brings quite a bit more bass to the table. Sure bass doesn't need a port or air, but it's a heck of a lot cheaper and easier than engineering a cabinet for optimal airflow. Trust me I work in the HVAC field, airflow is very complex.