Sony STR-DA1000ES Technical Background page 17

The STR-DA2000ES packs 120 watts per channel (20—20,000 Hz, 8
ohms, 0.8% THD). Yet the output transistors generate so little heat that
they can be mounted directly onto the S-Master Pro circuit board and
cooled by heat sinks less than one inch high!
Heat is always bad for electronics. That's why the heat thrown off by
conventional power output transistors is a crucial constraint in amplifier and
receiver design. And that's why so many high-power amplifiers require massive
internal heat sinks, cooling fans, and chassis layouts that isolate the output
transistors at the back or sides. In contrast, the tremendous thermal efficiency of
the S-Master Pro amplifier changes everything.
Instead of isolating the power output transistors, Sony can place them in
the middle of a circuit board. Instead of massive aluminum heat sinks, the S-
Master Pro heat sinks can be quite compact, especially on the STR-DA2000ES
and DA3000ES. And instead of a complex, circuitous signal flow, driven by the
need to hold the output transistors away at the periphery, the S-Master Pro signal
flow can be refreshingly simple and straight.
ES Receivers V3.0
Simple and straight design
Page 17