For loud concerts, you will need the BB.
Compressing the sound means compressing the dynamic range. An extreme example are television ads, in which the volume for everything is the same, no extreme highs and lows. A typical concert which have extreme wide variation in dynamic range, and other than jumping up every 30 sec to adjust the volume, one trick is to compress the highs and lows. I like to use it, but only slightly.
When you get a wave editor, you'll see. D/L a two minute concert and see the wave form with and without compression. Then hear the difference. The television add will look like a 2x4 instead of having a broad zig zag pattern.