So, I luckily came across a pair of JBL 2470 compression drivers set into JBL 2345 radial horns. (at a thrift shop...for $20!) They have fresh diaphragms and sound great. I also have laying about, a pair of JBL 123A low frequency drivers that sound great til their roll-off (2500 hz). I am thinking of experimenting and setting these up together to take a listen, the question is, the compression drivers are 16ohm rated and the low drivers are 8ohm rated. Would the math still apply as with normal parallel wiring resulting in a total of 5.33ohms? And, along the same lines, how would I figure building a simple high pass for the horn? (the 123A low frequency drivers a traditionally allowed to run full range, as JBL had always implemented them) Would it be for 16 ohm?