ART Pro Audio SDA1 - Studio Digital Amplifier - Manual (Page 4)

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INTRODUCTION
Thank you for purchasing an ART SDA-1 Studio Digital Amplifier - and
congratulations: you now own one of the most versatile amplifiers available.
Offering a superb level of sound quality, the SDA-1’s clean and powerful
circuitry combined with a straightforward user interface quickly and easily
delivers the power you need for professional and project studio monitoring.
Why would you choose a Digital switching amp over an Analog Linear amp.
Theoretical power efficiency of class D amplifiers is 100%. That is to say, all
of the power supplied to it is delivered to the load, none is turned to heat.
This is because an ideal switch in its on state will conduct all current but has
no voltage across it, hence no heat is dissipated. And when it is off, it will
have the full supply voltage standing across it, but no current flows through
it. Again, no heat is dissipated. Real-life power MOSFETs are not ideal
switches, but practical efficiencies well over 90% are common. By contrast,
linear AB-CLASS amplifiers are always operated with both current flowing
through and voltage standing across the power devices. An ideal class B
amplifier has a theoretical maximum efficiency of 78%.
Advantages
Despite the complexity involved, a properly designed class D switching
amplifier offers the following benefits:
 Reduction in size and weight of the amplifier,
 Reduced power waste as heat dissipation and hence smaller (or no)
heat sinks,
 No need for internal fan cooling,
 Reduction in cost vs. weight due to smaller heat sink and compact
circuitry,
 Very high power conversion efficiency, usually better than 90% above
one quarter of the amplifier's maximum power, and 50% or better at
low power levels.