hmm okay. if you are going active (i'd suggest it too), then there are plenty of options. just a guess that the xxx mids cannot play high at all so i'm guessing you need a tweet that can be crossed low. if you can fit a large format tweet then you can maybe go with the dayton rs28a or any of the seas large format tweets.
if you want a compact tweet look into seas lotus ref tweets, since they can be crossed very low ( i have them crossed at 1.6khz right now). but again depends on the budget though.