Well the placement is mainly goingto reinforce the lower frequencies.
Depending on your preferences, that can be Ok or not.
If you want to reduce the bass then yeah you need something to dampen the bass waves.
One cheap classic is piles of newspapers in the corners. (big piles, as tal las speaker) so if your foam is useful down in the lower frequencies, then it may help. If it is not, then the foam there is really wasted.
Toe in of the speakers may help considerably in lowering some bass peaks.
Depending on your preferences, that can be Ok or not.
If you want to reduce the bass then yeah you need something to dampen the bass waves.
One cheap classic is piles of newspapers in the corners. (big piles, as tal las speaker) so if your foam is useful down in the lower frequencies, then it may help. If it is not, then the foam there is really wasted.
Toe in of the speakers may help considerably in lowering some bass peaks.