Matt, the graph and Axiom specs on the M2 are somewhat better than you've described. Rather than "nothing" around 70Hz, the graph shows good response there and the spec cites 70Hz as the +/- 3dB point. Be that as it may, if used without a sub the M3, although less linear in response, does have at least 10Hz lower bass response.

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Enjoy the music, not the equipment.