ZERO LINK is the new digital audio signal (I2S, DSD) transmission standard established by SOULNOTE and SFORZATO. The key of the ZERO LINK is that the clock master is DAC not Transport. How to create the Best Performance DAC with inputs such as USB, LAN ? The conclusion by the two companies was eliminating asynchronous operation from DAC .  ZERO LINK is what makes this a reality. DAC works to convert digital data to analog signal in succession, to the rhythm of the sampling frequency . This rhythm must be maintained without disturbance, and must be kept constant. Data sent over USB or LAN comes at a timing that has no relation to this rhythm. A given amount of data is sent in blocks, which must be arranged so that DAC can read them according to its rhythm. The work of receiving and arranging the data, too, is carried out with timing unrelated to the rhythm of D/A conversion.

Imagine this. As you clap to a certain rhythm, next to you is someone who makes loud noises at times unrelated to your rhythm, beating a drum – tata, tatata, ta.... – at a completely unrelated tempo and rhythm. Wouldn't you want to shout at this nuisance to get out?

Completely shutting out hindrances to rhythm is the DAC portion connected through ZERO LINK .

It forces the USB, LAN that create rhythm-disturbing noise out to Transport. It then transmits the clapping rhythm from DAC to Transport, and sends data one item at a time in step with the rhythm. The result: no noise inside DAC other than your own clapping, letting you concentrate on D/A conversion without disrupting the rhythm.

What connects Transport and DAC is ZERO LINK. The format (e.g., sampling frequency) of songs played by the transport is communicated to DAC, after which DAC sends a rhythm fitting the format to Transport .  Transport then sends data in step with that rhythm to DAC, piece by piece. The connection method behind this mechanism is ZERO LINK.

Diretta vs ZERO LINK 

Diretta is LAN communication, but ZERO LINK is tranport – DAC designated interface. They are completely different and cannot be compared.

Diretta minimize extra work load / work load fluctuation of DAC and gives good sound quality. However it is LAN communication. It is asynchronous to D/A conversion timing in DAC. It is not good to have asynchronous operation in DAC. To eliminate asynchronous operation in DAC completely, to separate LAN/USB communication from DAC is necessary. By connecting the transport and DAC with ZERO LINK, all operations in DAC can be completely synchronous to D/A conversion and there is no asynchronous operation in DAC.

Diretta and the ZERO LINK is targeting the same goal and the ZERO LINK is the ultimate. But again, ZERO LINK is just for transport – DAC designated interface and cannot be compared to Diretta which works in general purpose LAN.