Experience with Downfiring Subwoofer

@rock-on. you're probably getting floor and wall resonances if you're floor is suspended wood. you might consider some form of decoupling. 

my floor is also suspended wood. while i don't have down-firing subs, they still resonate through the floor. my solution is the subs on an isoacoustics sub stand on a paver on the carpet. i tried the feet, nope. the stands better. much improved with with stands on pavers. 

my towers are somewhat similarly set-up.

definitely does a great job reducing floor and wall resonances. 

that being said. everything you use will have it's own effect. i hated sorbothane. it truly sucked in my chain.

next up, granite plinths. they'll, at least look better. maybe, a small improvement in decoupling. 

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. 

I'm a fan of MK subs (push/pull). 2 in my front system & 1 avr duty.. 

The new generation is out of my spending zone, but they do look sharp! YMMV

Bass is basically omnidirectional so doesn't matter if down firing, or standard front firing. the bass will radiate in all directions.

@kofibaffour This isn't exactly true. What is true is by the time your ear can sort out what bass note is being played, the bass has bounced all over the room and that is why its omnidirectional.

But it does bounce. You want it to bounce as much as possible to reduce standing waves which can cause a boom or a loss at certain frequencies and locations in the room (IME at the listening position...). For this reason a down-firing driver will be a bit more effective if the cabinet has only one driver. 

If you have only one driver in the sub and its not down-firing, I've found it more effective to point it at an angle towards a nearby wall, so the bass energy has bounced around a bit. This helps reduce standing waves.

If the cabinet has outputs in two directions angling it is even more effective.