Actually class D amps with less negartive feedback are excllent cnadidates for soft clipping. Just change the original sawtooth or triangle waveform. Flletten it at the peaks. What's more it is impedance independent. Anything that ****s with the gian of the output stae will change with load. When you do it this way, it is constant. ;

You can sett your watcxh to it.