Perhaps you are refering to the yamaha Sub kick,
Subkick a type of microphone that doubles as a bass cannon to improve the front of house sound. You might think that this a gimmick, but big time drummers have been adding extra drums to the front for a long time now.
When I saw Bozzio in clinic, his two main bass drums had six inch counterparts mounted in front of them.
Having two bass drums myself, I can agree, there is a substansial difference between the two due to the sound that the right one makes, bouncing through my 14" floor tom. Try your bass with the floor tom in place, then move it out of the way and you should notice a difference.