Sony STR-DA1000ES Technical Background page 7

(B) audio elements
The action of the LPF. The audio signal (B) consists of low frequencies,
which pass. The red lines show the characteristic of the LPF, which
suppresses the noise elements (C) on the right. These are high
frequencies, which do not pass.
While Sony's S-Master Pro amplifier is simple in principle, the fidelity of
the output signal depends on getting each pulse exactly right. That is, the
leading and trailing edges of each pulse must have the right timing—and the
height of each pulse must be carefully controlled. This is comparable to the
requirements for Super Audio CD playback. So to accomplish these goals, Sony
used technologies developed for our legendary SCD-1 Super Audio CD player.
Sony's own CXD9730 Large Scale Integrated circuit (LSI) provides the
S-Master Pro processing.
The S-Master Pro process converts the incoming signal to a one-bit
Complementary Pulse Length Modulation (C-PLM) stream, after which the Pulse
Height Volume control sets the volume level. The S-Master Pro process is
performed by the Sony CXD9730, a proprietary Sony Large Scale Integrated
circuit (LSI).
ES Receivers V3.0
Low-Pass Filtering (LPF)
Frequency
The S-Master Pro process
(C) noise elements
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