“Balanced cable” sounds like a quality grade. It describes a connection job, and the equipment at its ends matters as much as the cable between them.

Before buying, identify the output, the input, and what they are meant to carry. A cable with the right-looking plugs can still connect the wrong kinds of signal.

What balanced actually means

The two signal conductors in a balanced connection have matched impedances to ground. Impedance describes how a circuit opposes current. A suitable receiving input measures the voltage difference between the conductors, which lets it reject interference common to both. How well the real circuit and wiring preserve that balance limits the rejection; hiss already carried in the audio signal is a different problem.

Many balanced outputs drive equal, opposite-polarity audio on those conductors. Others drive audio on one leg and match the impedance on the other. Both can be balanced. Jensen’s engineering explanation defines balance through impedances, not signal symmetry.

A TRS plug has more than one job

XLR commonly serves balanced microphone or line connections. A 1/4-inch TRS plug can carry one balanced mono channel, stereo headphones, or an insert connection. TS commonly serves unbalanced instruments; RCA consumer audio is unbalanced. Yamaha’s cable guide shows these roles.

A balanced line output feeding a balanced line input is one job. Connecting a stereo headphone output directly to one balanced mono input with a straight TRS cable is another: the input can subtract left and right, canceling material shared between them. The plug fitting does not make the connections equivalent. Use the equipment’s supported stereo connection or breakout path, keeping the left and right channel roles separate and checking the required levels.

When unbalanced is reasonable

A short guitar cable from an instrument to an amp is normally unbalanced by design. Nearby consumer devices may also connect cleanly without conversion. There is no fixed length at which every unbalanced cable becomes unusable.

A long run near power wiring or electrically noisy equipment gives interference more opportunity to enter. If the equipment supports a balanced connection, use that path rather than asking a premium unbalanced cable to supply it.

What a DI box changes

A suitable DI can convert an unbalanced instrument output into a balanced, low-impedance mic-level output for a mixer mic input. Radial’s DI explanation describes this change for longer stage runs. It is more than a connector adapter.

That output level matters. If you’re connecting a line-level source to a line input, a DI’s mic-level output may add the wrong conversion. Check the devices’ documented connection and whether the actual problem is wiring, level, or ground isolation before adding a box. For a DI that does fit, confirm source compatibility, required power, and whether its design provides the isolation you need; balance alone isn’t an isolation guarantee.

The buying decision

Write down the source port, destination port, and signal role and level. Use those details to choose the maker-specified cable or converter. Keep a short unbalanced path that is working cleanly. For hum, trace the existing connection and its route and level settings before spending more on a cable.

Updated October 3, 2026: corrected the earlier definition that required opposite-polarity audio on both conductors of every balanced connection.