Actually, both the two π and two π tower are well-damped in the acoustic filter sense, meaning that the Q of each of them does not rise to a point of being highly underdamped or peaky. So neither system has a bass peak, as is characterized by underdamped systems.The deal with distortion verses extension is really just a matter of excursion. For a given radiator size, the deeper you run it, the more excursion is required. So distortion goes up as the frequency goes down.
On the matter of amplifier choices, the Alpha 10 is extremely "tube-friendly," so you have a lot of choices. It will work on solid-state, push-pull tubes or low power SET amps.