I use the AMTPro in an OB design currently. If crossed properly it can be very engaging. Note that the PE frequency response charts were done in closed back mode, with the two thick felt pads installed. It is more erratic in OB mode w/o the felt in place.
I have spent many hours with this driver testing various combinations of crossover points and slopes. My personal favorite is crossing the AMTPro high with a shallow slope. Use a very high quality single cap such as a Mundorf Supreme (or better) and take full advantage of the fast transients and crystal clear presentation. Finally tune the OB response by placing one felt pad half way up the spine, with the other overlapping and slowly slide them away from each other while listening. Depending on your room boundaries, there is definite sweet spot that will be attained when the right amount of diaphragm surface area is exposed at the rear. Once you are happy with the "tuning", you can cut the excess off the pads and press them in place. (friction fit).
If you have a design that lends itself to this crossover topology, this driver is hard to beat. I understand that the AC version of the AMT is easier to work with than the Dayton, but have not tested this myself.
