Behringer compressor sustainer cs400 behringer cs400 p the behringer compressor sustainer cs400 will add amazing impact to your tone and provide endless sustain p p ever notice how some strings on your guitar or bass sound louder than others strings with lower mass just don t put out as much volume as the heavier ones when used properly a compressor makes all of the strings the same volume p p compressors are also great for slap style bass players making thumb slaps