The internet transports packeted data. Digital words made up of digits that have address information and sequence numbers so they can be transmitted through the internet and reassembled at the user site. They need to be received and translated. The translation usually occurs in a PC, phone, or iPad. The packeted data can be a email, photo, or music file.
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Before the data can be used... to produce an email or music... it has to be translated into a bitstream and then create a file.. if a email or music file. Since it is not practical to wait to receive a whole file and then play it for music and home theaters the process of conversion from internet packets to a stream of bits that a computer (or “streamer”) can translate has been made to work in real time. This is a stream of bits that can be passed on to a Digital to Analog (DAC) converter to converted to an analog signal that can be amplified and used to drive analog speakers.
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So, Ethernet / packetized data has to be converted to a bit stream before it can be converted to an analog signal. The streamer function can be in a PC, iPhone, laptop, or a high quality device called a music streamer. The output can be handled inside the device and passed on to the DAC in the PC, or iPhone, or it can be passed by a digital connection to an external DAC via USB, SP/DIF, or optical connection. This is a timed bit stream... not asynchronous packets.
I hope this helps.