I'm using TD-2002 drivers in DIY speakers using an active crossover. They were connected directly to the horn amp, but I noticed that the horn seemed to "stick out" a little at times, especially when reproducing female vocals. I tried a small series resistor from the amp to the horn drivers, and with about 2.7 ohms that fixed the problem. I'm happy that the solution was so easy and inexpensive, but I would like to understand the theory. My guess is that I'm "tuning" the decay time (waterfall) of the horn drivers to better match the woofers in the crossover region.