Ditto what Murph said. I leave mine at +3dB, not because the vp160 is lacking; just the opposite. It improves intelligibility and because the sound quality is so good, I don't feel like the sound quality is taking a hit by boosting the 160 a little over my M60s.
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::::::: No disrespect to Axiom, but my favorite woofer is my yellow lab :::::::