Bought a Toshiba 40D3453DB Smart 40" LED TV, and picture quality is excellent. The sound is not so. Found an old pair of Packard Bell PC speakers (stored for many years in the loft) powered with an inbuilt amp. Connected these to the headphone jack on the TV and they work well.
My question is, is this set-up ok for the TV and speakers or can it possibly create some damage later on?
I did something very similar with one of my TVs and had the same concerns as you but still working fine 2yrs on with no problems and much better sound quality so I don't think that you will have any troubles. I think that if it is going to do any damage i.e. mismatch it will happen as soon as you connect it in my experience.