Sony STR-DA1000ES Technical Background page 15

Conventional power amplifiers use separate transistors to reproduce the
upper and lower halves of the waveform. Crossover distortion occurs when one
power transistor switches off and the other switches on as the audio waveform
"crosses over" the zero point between negative and positive. This distortion is
particularly bothersome because it remains constant as the signal gets softer.
This makes the distortion more audible during the quiet passages of music or
movies. Conventional amplifiers combat crossover distortion with the output
transistor bias current of Class A/B designs. Ironically, this bias current
generates even more heat. So in fighting one problem, designers cause another.
Analog
Driver
Class B analog amplifiers introduce a "kink" in the audio waveform
where the wave passes between positive and negative. Treating this
crossover distortion is a major goal of conventional amplifier design.
Pulse
Driver
The S-Master Pro digital amplifier is immune from these issues because
the output transistors do not shape the audio waveform directly.
Because the S-Master Pro amplifier uses pulse density, switching glitches
get removed from the music by the low pass filter. The system is immune to
ES Receivers V3.0
S-Master Pro Benefits
No crossover distortion
+V
Audio Output
-V
+V
LPF
Audio Output
-V
Audio Output
Audio Output
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