Technically you can but it's not recommended. The st30 is a music speaker so only processes left and right. So the best you will get out of it is stereo.
It will probably sound better than your tv, but will still suffer similar problems. For example most people want a tv speaker so that the vocals are easier to hear. In this case the vocals still get mixed in with the left and right, so no better isolation for them. Where even the basic soundbar has a centre channel to help with that.