AES59 is the AES technical standard that formalizes the pinout (the function of each pin) of the 25-pin D-sub (DB25) connector for multichannel audio traffic.

In practice, this standard is universally known as the Tascam Standard, as Tascam was the company that popularized it.

Its main objective is to simplify the connection of multiple channels, replacing 8 individual cables (such as XLR or P10) with a single cable, saving space and organizing the installation.

The AES59 standard defines the pinout for two main uses:

1. Analog Use (Balanced)

For analog audio, the standard defines the connection of 8 balanced channels in a single direction. This means that a DB25 connector will be dedicated to:

• 8 inputs (IN)
  OR

• 8 outputs (OUT)

It is extremely common in audio interfaces, mixing consoles and preamps to connect multiple channels to a patchbay or other equipment. Cables typically have a DB25 connector on one end and 8 XLR or P10 (TRS) connectors on the other, known as "snake cables" or breakout cables.

2. Digital Use (AES/EBU)

The standard also defines an alternative pinout for digital audio in the AES/EBU (AES3) format. In this case, the connection is bidirectional:

• 8 input channels (4 AES/EBU pairs)
  E

• 8 output channels (4 AES/EBU pairs)

This allows a single DB25 cable to send and receive 8 channels of digital audio simultaneously between two compatible devices.