I get 70 Hz flat w/o any equalization or "boost". The F3 is at 65 Hz. The F10 is in the mid 50s. The driver is designed to push a lot of air through the port. To avoid port noise, the optimum port diameter is about 1.5". The only attenuation I get in the woofer is to compensate for baffle step and to crossover. The specific driver I use (ND91-4), is designed to do this. It is not a dedicated mid-range driver (I would chose something else for something like that). It is also not the best full range there is. But it is optimal to for a woofer in a small vented box. You really need to design some things on your own to become more knowledgeable on these things. You are very outspoken. But seem to understand little. This is different from what many here mean by active XO. This is indeed one way to do things. However, digital manipulation only works optimally on a particular listening location. It is up to the drivers and system to perform optimally in as large an area as possible, or not depending on the goals. There might be other consideratons, such as pairing specific equipment with different characteristics. I've seen what you are doing. And it's a good solution. From what I've gathered, you are not shooting for an omni-directional response with large drivers at the expense of sensitivity (like Linkwitz). It seems you are aiming for high sensitivity and synergy with a carefully selected amplifier. You are not averse to equalization and you take care not to overdo it. Your system seems more alike what one finds in certain theaters. You have experimented with a lot of different designs, and have arrived to what you currently have through your own efforts and experience.