From 200Hz up, maximum SPL is about 10dB louder. Output over most of the audio range can safely reach 120dB, which is pretty loud for a 100 watt loudspeaker system. From 200Hz up, the horns increase maximum safe output and decrease distortion, but bottom octave excursion and IMD are the weakest points of a design like this.

I think most people that are attracted to the eight π speaker will be using it with tube amps so excursion isn't an issue. It will be very nice with a little 30 watt Class A transistor amp too, or with a simple chip amp or a receiver up to 100 watts per channel. Those are some of the systems I would recommend for use with the eight π loudspeaker.