The best configuration you can get for a sub could be a dual opposed side firing driver configuration (ie two opposed drivers in the same box)., in consideration of how subs couple into a room...and what all happens thereafter.
Experience with Downfiring Subwoofer
Colleagues:
SITUATION: I own a pair of Monitor Audio Bronze W10 subwoofers. They are down-firing units. Placement will be on Berber carpet with heavy padding on a wood composite second story floor. The units are designed to have the amplifier set upon 4 feet approximately 2 inches from the ground.
QUESTION: Recognizing the down-firing speaker radiates sound outward in all directions on the floor, what are your experiences in leaving the feet on a carpeted surface, solid platform, or on a raised subwoofer/equipment platform?
Thank you for sharing your experience and insights.