After thinking about this more... They MIGHT have dynamically compressed the loudest bass for the digital version. IF that's the case, simply turning up the bass won't fix it because all of the bass would be turned-up.
Although CD has a wider dynamic range than vinyl, there is an absolute digital upper-limit of 0dBFS... You can't just keep making it louder to the point where the stylus jumps out of the groove. They would have had to make the rest of the recording quieter and they may not have wanted to make that compromise, so maybe they made a different compromise.