Why dont more standalone DACs come with ethernet???

Well a stand alone DAC with an Ethernet connection is called a music streamer with a DAC.

The streamer converts packetized internet signal to digital bit stream. This process if done correctly requires a high level of sophistication and a box.... is a stand alone component. The DAC then converts the digital bitstream into a line. Level analog signal that can be amplified in the analog realm. Done correctly it requires high level of sophistication and a box. They can be combined... but usually there are compromises. 

@treebeard1. “However, many DACs take ethernet direct and there is no need for USB...”

.

Then that is technically a DAC with a streamer. A pure DAC will not have that function.
.


There is the streamer function, the DAC function, the preamp function, the amplification function and the speaker function. They can be all in a single devise or in a combination. The connection types vary between the function if in different boxes.

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.

.

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.
.

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.