Is it possible to shield unshielded speakers?

Dweller is right -- to expand on that just a little, I've always noticed the distortion on the edges/corners of the picture. The color may be saturated or the picture distorted. Even small distance separations can make a big difference since the strength of the magnetism increases on a squared basis with distance.

BTW, I presented the aluminum foil idea as a hypothesis above. More knowledgeable members shot that one down, so I wouldn't encourage anyone to follow that route. To reassure yourself, just put some aluminum foil on the outside of the speaker box -- surface closest to the TV. If there is no change, you've only wasted a few seconds of your time.

Ozfly: I think the trick is to ground the aluminum/copper foil.
When a magnetic field passes thru copper, electrical current is produced.
Give the current somewhere to go (ground) and the field is no longer a problem.

I had this very problem myself once.I mutilated a pair of old bookshelf speakers laying around and cut the magnets off of the drivers and used them as bucking magnets.You wont need to glue or anything,the magnets will hold together just fine.Just for the record,I am not familiar with your particular speakers as far as size of drivers but mine were 10in 3 ways that I was shielding and the 4-5in midrange didnt even need it just the 10in driver.I agree with the others,I wouldnt do anything untill you do have a problem,you will know if the drivers are messing with the picture or not.

LCD tvs do not cause a problem

Epoxy bucking magnets to the back of the magnets of your speakers. You can buy the bucking magnets from parts express
and other places.