Subwoofer with Floorstanding Speakers?

+1 jpan. The room will be the key. As stated already I would run your speakers full range and set the subs crossover low to start. Good luck ! 

bigtex22, I am not familiar with your equipment and can't know if the amp is enough for the speakers. But I didn't mean just power ratings, it is much more than that.

If you go subwoofer route to begin with just make sure you can return the subs in case you don't like what you hear.

Of course, the room is always extremely important.

When you see live music, the bass and sometimes keyboard players have 18” or bigger speakers.  

I spent a lot of money building a smallish (3.3 x 4.5 m) listening room, it sounded terrible. The bass was so overblown that the cones of a pair of unconnected speakers in the room would be moving.  One wall in particular vibrated and sounded terrible at any appreciable volume. I spent money on all sorts of passive solutions that helped but did nearly solve the problem. However I used 2 subs connected to my pre amp via a minidsp, cut pass to my Audio Physic Sitara 25's floor standers and plugged there ports. Set minidsp to cut at the 3 room mode frequencies.  Problem solved, no awful bass, no rattling walls, until volume is set on crazy, so my experience is yes subwoofers were definitely a massive improvement. Sounds stunning too.

@bigtex22 My room size is 13ft X 18ft. I bought 2 JL212 subwoofers to compliment my Kharma Exquisite 1E Signature. The subwoofers are very important as they provide the foundation for full bodied to the music especially jazz and rock. I recently bought 2 Funk Audio LX21.0 which greatly improved the emotions to the music. The software for tuning the DSP of the Funk subs  is very user friendly and easy to setup. I recommend you to go for the Funk LX18.0 or the Lx21.0.

Happy listening.