"Maybe there is a relation between Bam and bass hump"
Pojuojuo, it is interesting that you hear a mid-bass hump or boost, must be a room node as Bobby notes. I have never had a mid-bass issue with the VSM-M which I have used for 12 years now, but it took a while in the early days to get the low bass right including dialing in placement, room treatments, isolation devices and matching the right components. I might have welcomed a mid-bass hump in those early years, cause the balance wasn't right but I perservered recognizing the other aspects of their presentation with the encouragement that yes, the speakers do bass.
Until you REALLY get things right, dialed in, it might seem that the speaker doesn't do bass but still.... I never had the hump issue you are experiencing. This is one of their virtues, especially for a 2-way, no humps, no gimmicks. The low bass articulation, control and pitch accuracy of instruments is just unbelievable when it is right. I'm not too sure I have heard well recorded solo piano sound more natural, coherent and resolving top to bottom on any system regardless of what John Atkinson said in his comments in the Stereophile review. ;^).
