That's exactly what you must do, but mount the driver to the horn before mounting the horn to the cabinet. The thing to do is to preassemble the 2426/H290 combination, so that you know everything fits. Then take the assembly back apart and put the horn in the baffle cutout, and re-attach the compression driver while the horn is still loose. That way you can move the entire assembly around to get access to each of the bolts.It's really not too bad. It isn't as easy as the PSD2002, since it uses two-bolt mounting and will fit through the baffle cutout. But with the horn loose in the cabinet, you'll find that assembly isn't too difficult.