I'd like to make this real simple. Speakers are made specific to a frequency/wavelength they're trying to reproduce. A sub wavelength can be as long as 32 feet while a mid-range frequency could be as long as 2 feet long. I won't get into specifics because nobody cares. Bottom line, a 6x9 does NOT produce the frequencies/wavelengths that a 8" dedicated sub is designed to play. Therefore, if a 6x9 doesn't play sub frequencies...how can you honestly tell people "it adds a little bass". That's only because it has similar cone area to an 8" sub. BUT that doesn't mean it is playing sub frequencies. It just means that mid-bass is playing lower.
Again, 6x9 will never equate to 8" sub. 8" mid-range will never be the same as an 8" "sub-woofer". Words have meaning. Stick to them. The quicker people start to realize that words are specific and not generalized these conversations will be much more concise.
I pointed out an open air sub AND a sub that required a box. 6x9's in the rear are no good unless you're doing something fancy that I don't want to talk about
Hope this helps!!
