As for the XO, I think I'm gonna buy another amp and a 3-way active XO and tri-amp the whole thing. I'm already bi-amping with a 2-way active XO and I've been wanting to go 3-way anyway. Dialing in the correct XO pint will be alot easier all the way around. The PE drivers are #265-568 (extended range) and look to have useful output between 150hz and 10khz in a sealed box, with a nasty peak between 7khz and 10khz. My original thought was to start at 7khz to avoid the peakiness and I wanted to hear the 6.8khz comb effect - I'm more interested in learning something by this project than anything else. If I go active on the XO, I can just dial it anywhere I need it and get a quick feel for how the array behaves. I'd try to cross at ~150hz to my stereo subs, but they're big 18 inch drivers and I don't know how high I can go with those yet. An OB version would force me to cross at ~200hz and I don't have alot of faith in the subs at that point. The 4th order slopes will help and I'll have some gain control between the 4 inch driver array and the tweeter array.

Anyway, thanks again Jim for your input. We'll see how it all turns out.

Allan