PBP Dampened Sine Wave

Hi,I'm new here.I'm trying to produce a dampened sine wave via the PWM in the audio range but this is non critical(I'll wind up playing with the frequency eventually for what I want).I'm using a 12F675 at 20Mhz.Have a nice buffer on the output.Did a 'freqout' that sounded pretty decent(should probably beef up the filter on the input to the buffer a little,though).Tried doing something that sounded amusing but not even close to the dampened sine I wanted.Would eventually like to be able to alter a few of the parameters in real time.If anyone's played with getting sound out with amplitude adjustment(without having to include a VCA),would appreciate any suggestions.-Keith