There is currently a thread on the same driver on diyAudio. Go search that out if you would like more detail.
It is VERY hard, nigh impossibke to get bas sout of these. They are best as a midTweeter. They make for quite a good one.
Subwoofers do not go high enuff, they will rarely blend well.
The ML-V you have pictured looks quite interesting. If well designed it might be producing some semblance of max bottom from that driver. More pictures?
If you want bottom, you need to XO them above 200 Hz (about as low as they reasonably go), 300-500 Hz would be better. to helper woofers.E108e∑ trades some sensitivity for greater bas scapability, it does work well in a big horn, but you are still limited to above 50 Hz or so.
dave