I don't think the white is really the problem, I think it's more the drop shadow on the text that needs some tweaking. First, I would remove it from the black text and apply it only on the red. Then, I would bring the opacity back up to darken it a bit and lower the distance by maybe 1 point or so to bring it in a little closer to the text. That should make the red text pop more allowing you to lower the opacity of the white just a bit if it's still an issue.