“midrange base which is what I am lacking from the front area of the room”
I’m not sure I understand what part of the frequency spectrum that you’re talking about. When you say “midrange bass”, I’m going to assume that you’re talking about the middle of the bass frequencies, somewhere between 125hz & 175hz. Correct ?
Because you’re talking about such a narrow band of frequencies, this sounds much more like an acoustics problem rather than a speaker problem – namely ‘comb filtering’. I would like to suggest that you do some research in this area before doing any changes to your speakers. There’s some very good information/videos at
www.realtraps.com.
I don’t think your changes will get you the results that you’re looking for. Although adding more drivers to your speakers will alter the sound, I doubt that it will increase the mid-bass like you think it will. The changes you’re proposing will basically do two things – 1) decrease low-bass response with little impact to mid-bass, and 2) alter the loudness balance that you’ve set up with the other speakers in the system. I agree with the other posters that this is not the proper way to solve your problem.
However, if you’re bound and determined to try your idea, this is what you have. In their original configuration, each of the two driven drivers would be 16 ohms (assuming that the manufacturer has both drivers playing the same frequencies evenly) – the amp would see a total load of 8 ohms at the speaker terminals on the back of the speaker as your manufacturer has stated. If you add two more drivers with 16 ohms each (supplied by your speaker manufacturer) and wire them in parallel, the amp will see a total load of 4 ohms at the speaker terminals. This would result in a speaker that plays louder across the drivers’ entire range, not just the mid-bass. If you wire them in series, this would result in an amplifier load of 16 ohms, which in turn would result in a speaker that plays quieter, again across the drivers’ entire range, not just the mid-bass. Either way, all you would be doing is throwing off the impedance and loudness balance with the other speakers in the system. After recalibrating, you probably would still be dissatisfied with the mid-bass.
One of the previous posters suggested an EQ. This may work, it may not. It depends on how severe the comb-filtering is.
As I mentioned earlier, I think you would be better off doing some research on acoustics before altering your speakers. I would think you’d be happier with the end results.