dB just implies 20log_10. A reference must be selected. The most common are dBV (1 volt = 0dB), dBm (0dB = 1 milliwatt into 600 ohms), and dBSPL (watts relative to threshold of hearing at 0dB). I suspect that the implementers of this were thinking about the approximate 96dB of 16 bit audio, and the +/-1.0 float recommended max range of STK. Thus a range of 0.00001=0dB to 1.0=100dB resulted. Easy to change to any reference by just subtracting/adding/multiplying/dividing by a constant. PRC