Cutting sounds below 40Hz is not as brutal as it sounds. Although, in theory, audio range goes down to 20Hz, in practice a pure single frequency sine wave at 40Hz is very difficult to hear by most people, even the young and fit. A double bass plays fundamentals at that frequency, but if you were to filter out the fundamental, and just hear the overtones (harmonics) the bass would still sound to be at the correct pitch.
Your brain can tell what the fundamental frequency should be. (Law of the missing fundamental)
We are so insensitive to low frequencies, that is it very easy to have very high levels in the low bass without your knowing. If you use compression, however, the compressor will take its cue from the loud, but inaudible, bass signal, and the result will be a recording that looks loud when you see the waveform, but sounds quiet.
Matt Keen has my support in recommending Sound On Sound. Paul White and Hugh Robjohns are both friends and neighbours of mine.
Where did you think I learned all this, well enough to teach it for fifteen years?
Cheers
Dave