Below is the files necessary to enable LLE (Low Level Emulation) DSP for Dolphin Wii emulator. One reason to use it instad of HLE is that you can now listen to the BGM in games such as Super Mario Galaxy 2! Be careful though if your CPU is not powerful enough there will causes major slowdown in the game. You might even heard audio cracking but it's fine.
Extract and place them under your Dolphin Path\User\GC.