I THOUGHT ALL SOUND TRAVELED AT MACH 1
While it is true that all sound moves through the atmosphere at a specific rate relative to the atmospheric pressure and temperature, all sound is not launched at the same time. This is obviously true for disassociated sources of sound but it is not so obvious when the individual elements of our speaker system are taken into consideration.
We have tweeters, midrange, woofer and now the infamous subwoofer. Why infamy, because it is a highly touted product that the high-end has grown to hate. Audiophiles assume that it must work while in actuality it is a musical short circuit 90% of the time due to driver/cabinet resonance. With tweeters and other drivers not operated at resonance the waves are launched in a precise manner not influenced by mass. The crossover and driver arrangement can be cleverly designed and measured to provide repeatable results. The shorter wavelengths launched by the main speakers can be positioned away from the walls so as to have a benign interaction with the rooms reflections therefore allowing a bass of predictable quality but shallow depth.
Typically the high-end speaker manufacturer will not attempt to produce the sub bass frequencies from the design for numerous reasons. One of the main reasons is the difficulty in finding a good location for the entire spectrum of frequencies to be launched. Most full range loudspeakers sound best when located away from the walls (for mids and highs) reducing the bass support from the boundaries. Intermodulation distortion can result from some designs when an attempt is made to lower the frequency response of the woofer. In general it is best to obtain the lowest end of the spectrum using an external system that does not operate with a resonant signature and is not influenced by the rooms reflections.
The current subwoofer, borne of the attempt to provide large-scale effects to movie theaters and eventually to homes, had not been analyzed thoroughly for its effect on the rest of the sound spectrum. It simply does not move air when it is told and does not have the capability to stop moving when it is asked to stop. The sound travels at the same speed as your mains it is simply delayed in response due to mass and has a resonant signature which delays its ability to stop moving.
An old proverb states, "let each man walk to his own beat however different" and this results in the world as we have it today. The subwoofer however, must "walk to the beat of the main speakers" if it is to exist as an acoustically unified part of your music system.
In the event that you think that you have found a conventional subwoofer that is as fast as the Magellan's in your system the next question for you and possibly that significant other is do I have to see to that big box?