If you run multiple piezos in a cab you can wire them for more power or more sensitivity. Wire parallel and you get increased SPL of 6dB/doubling of drivers, but with no increase in power handling. But if you wire in series the SPL remains level while wattage increases by a factor of four for each doubling of drivers, so two 50 watters in series will handle 200 watts, and four would handle 800 watts.