You have to mount the cabinets so that the HF horn is at least 1 foot above the patrons heads. Any lower, and the HFs will be blocked by those closest to the speakers. You will get no penetration. It is a fallacy (mostly) that you will get "more bass" by putting them on the floor. What you are really doing is blocking the highs, not increasing the lows, causing you to turn up the HFs. Subs make great, stable, speaker stands. Don't leave home without them.