It's interesting that there are now speakers that do their own D to A conversion, but I have to ask "Why".
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Hi, my first post
Speakers being inductors can be used to filter high frequencies out.
Digital signals are either on or off, so a pulse (wave) will have very steep edges.
The steeper the edge, the higher the frequency content.
So if you can embed a direct digital representation of an analogue wavefoms power signature in a digital stream, you can amplify this in the digital domain (with a Digital Power Amplifier), then the high frequency digital edges are filtered out by the loudspeaker, averaging out leaving the analogue signals waveform.
There is a method of transmitting digital information such that when shown on a graph, the power under the PWM signal can be averaged to follow the curve/power of an analogue wave.
This is called PWM (Pulse Width Modulation), it is a single stream of data known as a Bitstream.
The idea is that the longer the bit or pulse width (ie the longer it stays as 1) "in a time frame", the higher the power.
The shorter the pulse width, the lower the power.
The PWM sample rate is many times higher than the audio frequency range, typically 384K samples per second to 1M+.
This means that a single pulse doesnt represent a wave directly, many pulses represent one analogue wave (typically 8 or more).
The amplifer must amplify the PWM bitstream so must be a digital amplifier.
It is fed with the PWM bitstream so other digital signal types need converting before being fed to the amp.
A Digital amp may do some conversions, it depends what the mfr implements.
Some advantages are that there is little to no phase distortion, they are highly efficient, smaller, lighter, cheaper to make.
They can provide very high power, maintaining a clean signal much easier than analogue amps.
I hope that helps.
(I know about the tech but havent heard a digital amp yet, its on my to do list)