Such systems place the highest priority on going loud and to do so in such a small space requires several large diameter long throw woofers (long Xmax) - plus huge amplifiers to push them to their limits or beyond. Most require the entire trunk so if you want to store anything more than a napkin back there, you're out of luck. It is pretty cool to listen to one of the better setups at reasonable levels and for a short period of time, but audiophile-demanding bass extends far below what the vast majority of these systems do well.
Such systems focus on over-emphasizing the acoustic merits of two instruments: the kick bass drum and the bass guitar. But just what are the lower frequency limits of these instruments? The lowest frequency a kick drum creates is between 80-100 Hertz, depending upon its size. The lowest note a four-string bass guitar can create is low E (the same note a classical acoustic double bass can create) and its frequency is 41.21 Hz. So to get linear bass down to this point, the lower limit (-3dB point) of the bass system must be at least 1/2 octave below that (say -3dB at 30 Hz). But in such systems, linearity is not the goal but overemphasis of frequencies between 40-100Hz is, so systems are tuned to have a rising response specifically in this region.
Inexpensive subwoofer add-ons to home theaters do about the same as these extremely loud car systems: they get reasonable bass at loud levels. Theaters also have joined in on such a bandwagon extending this niche to over-emphasizing specific noises in sound tracks like fist punches and the good-old random explosion, but again deep clear bass is not the goal.
Long-throw woofers, while providing deep bass from a small box, increase the distortion of the bass as an exponential function of the travel. Take for example a woofer with an Xmax of 6mm. If the volume desired moves the woofer in and out 0.1 mm, the distortion will be quite low. But as the sound pressure increases (piston travels in and out over a greater excursion), so does the distortion. At a cone travel of 1.0mm, the distortion may be 10 times that at 0.1mm and at a cone travel of 2mm, the distortion may be 100 times that at 0.1 mm. So the louder the bass from such a woofer, the higher the distortion will be as its Xmax is approached.
|JL Audio 12W7AE-3, Xmax=29mm|
As the level of an audiophile's ear becomes more discriminating, just like the pallet of a wine connoisseur, listening to such systems for prolonged periods of time becomes intolerable. Like trying to appreciate Boones Farm in a 5-star restaurant, some things just don't quite mix.
One day, if their hearing is not totally destroyed by the carelessness of their youth, such folks will turn their attention to refinement and what sounds real. At any opportunity, take one of these misguided youths under your audiophile arm and let them hear what a good system sounds like. Then crack open a good bottle of wine and both of you sit down and enjoy some music.