Thanks in part to ideas born at dB Drag events, the acousticpower of car stereo speakers has increased tenfold in the last ten years, from a maximum of 500 watts per square meter to 5, 000. (A loudspeaker at a rock concert puts out 2, 500 to 3, 000 watts.) Pioneer learned from dB Dragsters to cover speaker coils with ceramics to dissipate heat.
This makes it easier to scale up the number of disks in the drive while keeping drive power consumption and acoustic noise at acceptable levels (and even lower than the air filled drives).
Magnets work to either increase of decrease the string's motion, bringing out vibrational modes that have always been in-play on acoustic instruments, but have never been offered the power needed to make 'em sing.