I want more bass…

The first place I would start is repositioning your speakers. Even before you do that you can try reversing the phase at the speakers by switching +/- cable connections. If the bass is "better" then it's not the speakers themselves but rather their location in your room relative to where you listen. It's an easy test.

I vote for the room. Either you are sitting in an area with a suck out or your expectations are not realistic. I would start with taking some measurements to see exactly what you are getting.

As others have stated, it’s probably your room and/or speaker positioning and listening area. Some extensive measurements and rearranging will probably be in order. 

A great tool to help you with results of positioning in your space is a Sound Pressure Level Meter. Amazon.

put on tripod, listening position, seated ear hight, see how balanced the range of tones are. move the speakers, listen, then run the test tones, see the results.

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combined with a test CD with test tones.

I have this one, got lucky, bought long time ago when affordable, very pricey now.

tracks 9-38 1/3 octave test tones.

you want specific individual tones, not sweeping tones.

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OTHERS: what CDs are good for test tones????

With four 12" drivers and "not enough bass"....I'm very suspicious of the room. 

Even though you don't have a subwoofer....do the subwoofer crawl around the room, on your hands and knees, sometimes moving your head up and down and see if there is good bass ANYWHERE in the room.  If so, then speaker positioning vs listening position adjustment will be critical.  If not, then you just might have one of those room that has so many cancellation modes that these speakers just aren't going to work in your room.