If you are looking to add some more open/airiness due to a bit of reflection then adding a smooth surface floor at your speaker end will do this. Hardwood would probably be a good choice ( as "natural wood" is certainly "Natural") but be careful what you're wishing for. If you sense that your system seems just a bit too 'damped' or lacking a bit of decay...this would be a step in the right direction. When I was building my [dedicated] room I weighed the ups/downs of different flooring. I have a concrete base which I covered with a product called "Dri core" (avail at Home Depot) then topped it with a vinyl flooring called 'Allure' (also from depot...) I left approximately 1/3 of my room (speaker end) with the Allure and the back (behind my listening chair) also with the Allure ( which amounted to approximately 3' or so). The center part of the room I placed a medium density carpet (above its own [felt-type] padding) and it worked out quite well.
In my mind the theory was to let the speaker floor area "breathe" without added absorption as well as the final few feet behind me with the same idea...The In-Between would be somewhat 'tamed' by the carpeting (as well as via the extensive room treatments placed carefully throughout)...
It's truly a case of experimentation. As a side note: I actually had 2 additional sections of the carpet cut and bound for me when I bought the main one...I made them each the width of the speakers (about 30" each as I have planars) and the actual length of each as the distance [behind] them to the wall ( I refer to as the front wall); just so I could freely add/remove to compare the sound. I knew I wanted most of the area sans carpet but I also thought it would be interesting to add some just to effect the rear wave (dipole) of the speakers. After auditions with/without I settled on going without the additional 2 pieces as I felt it was a better balance of the aforementioned 'openness' and air...
In theory your hardwood should be better than vinyl?...in as much as it is, as I said before, more natural...but will probably add even more of this effect.
If you can try something a bit make-shift at first, maybe you can figure out some way?, I can attest that even with a fwd firing dynamic-driver speaker such as yours, there will still be some [possibly promising] effect for you. Good luck and happy Lissn'n
