The Mono Button
Most systems play the bass in mono, and a bass widened for headphones pays for it there. A 10 ms delay on one side reads as out of phase and takes 16 dB off a 55 Hz bass in the sum. A detuned pair pumps in mono every 1.6 s, 54 dB deep. Sum and difference combs are as wide as either and lose nothing at all, measured.