Can I assume that you are mixing in mono? If so, and you are feeling creative (you may not be!) you do have the option of running the active full-range speakers from the two left outputs and the bins from the two right outputs (just a jack-XLR adaptor or similar cable required)
That way by shifting the pan control left or right you can alter the amount of any channel that is running to either set of speakers. Full left = Titans only, Full right = Peavey bass bins only, central = 50/50 split
It would enable you to run the bass-heavy channels more into the bass bins and vocals (for instance) only into the full range Titans.
Not a perfect solution at all, but would cost less than a tenner to try out...