Give it a Tilt!
(Tilt your speakers backwards for a new experience!)

There are speaker manufacturers out there who go to great lengths to achieve time-alignment in their speakers, which is to design their speaker driver arrangements and baffles such that the sound from the drivers arrive as a coherent source at the listener's position. Thiel loudspeakers has an informative FAQ on this. Ok, for those who have not the time to read that FAQ, here's the summary : "Sloped baffles (can) result in better(?) sound". : )

Sloped baffles do more than just time-alignment, they also reduce standing waves inside the cabinet since the front baffle and the rear cabinet walls are now not parallel.

But for those of us who do not have sloped baffles to start with, myself included, for matters of time alignment (actually, IMHO, in my case, room acoustics seem to be the culprit for the difference), I have to make do with tilting the entire speaker backwards by a small angle as shown in the picture on the right.

Things that you will need:
3 or 4 adjustable cones for each speaker
double-sided tape (Now this is quite important! You do not want your precious speaker to spill its brains out falling backwards!)
Alternatively, you can use
3 or 4 fixed cones
2 pieces of padding material to put under your front 2 cones. I would recommend small bitumen squares. But then again, anything goes, as long as your ear agrees, wood pieces could work too.

But try to secure everything firmly!
double-sided tape

Yes, result results results... sadly, that is what most audiophiles / audionuts are concerned with. (The process by which something is achieved can be as interesting and satisfying as the result itself). For me, I managed to get more perceived depth out of my soundstage. The characteristic also changed towards a more laid-back nature. No, I do not attribute this to "time-alignment", my results are probably due to a combination of room acoustics effects (why do I say this, for my speakers are not "time-aligned" to my listening position after I did this tweak, but rather, the angle of the drivers with respect to my room walls and my ears were changed. )

Well since this is a cheap tweak, give it a shot! "You'll never know what you're gonna get!". Then perhaps you can share your results with me and I shall "publish" them here for the benefit of others.