The lowest note on a string bass has a fundamental pitch of about 40 cycles per second. At a live performance,the difference tones add an ambiance to the bass that is usually not present with recordings-even with a subwoofer.
Difference tones? See The Psychology of Music By Carl Seashore for more on difference tones.(Quick take,a 40 cycle tone creates an "undertone" at 20 cycles,that creates an undertone at 10 and so on.)
The "Krell Sound" as I understand it,is an attempt to recreate the bass response of a live performace by what many call "bass grip".
Other posters have mentioned that componant matching is important and I agree with them.
