ja det verkar som att desto mer ljudförstärkande ytor basen har vid sig desto mer "boost" får man,

"When sound is radiating 360° it is said to be radiating into full (spherical) space (4π steradians).  When you place this speaker against a boundary, say the floor, you are now radiating into a hemisphere or half space (2π steradians) and the SPL increases by 6 dB.  When this speaker is placed at the junction of the floor/wall, it is radiating into a quarter sphere or quarter space (π steradians) and the SPL increases by 6 dB.  When you place the speaker in a corner, it is now playing into one eighth space (π/2 steradians) and again, the SPL increases by 6 dB.  This means a theoretical increase of bass on the order of 12 dB (from half space to quarter space, then to one eighth space) if the speaker is placed in a corner.  In reality, rooms have doorways and windows and not totally rigid walls and speakers that are generally a few feet away from the walls.  All these factors allow for some loss of bass so that corner loading usually contributes around 7 to 9 dB of gain in the bass frequencies beginning around 50 Hz or so for small rooms down to maybe 20 Hz or so for large rooms."

så desto fler ytor runt omkring basen desto högre db ökning, typ som du beskrev det, det funkar som en ljudförstärkare.
om du har basen mot golvet så funkar det som en spridning och du får en 6db ökning, sen om du ställer den vid en vägg/ner mot golvet så får man 6db ökning till i basregistret etc, om jag nu inte fattat det helt fel,