     The author of the Class D section, imo, seems to be confusing Class D amplifiers with Digital to Analog converters (DACs) - the only reason that they are considered digital is that the output devices are only ever in one of two discrete states (saturation/cut off). There is never any conversion of the input into numbers, and most of the distortion is due to the modulation, not the quantisation of the signal.  That is only the opinion of an undergraduate EE student though, if anyone feels more qualified to respond, please do.  -Stuart (March 22, 2004)