According to
http://www.magnepan.com/1-800-474-1646/r-mg16.html the specs for the Magneplanar MG1.6QR are
Frequency Response: 40 Hz - 22 kHz ± 3 dB
Power Requirements: 100 watts RMS (8 ohms), normal; 250 watts RIMS (8 ohms), maximum
Sensitivity: 86 c1B (2.83 W500 Hz/1 M)
Impedance: 4 ohms
Crossover: Acoustical, 600 Hz, Low-pass (quasi) 12
dB/octave, high-pass 6 dB/octave