An audio circuit with 3 wires, two carry the signal, and the third provides the ground. Compared to an unbalanced circuit using a single signal wire and a ground, balanced signals are much less susceptible to picking up interference. Therefore, professional sound recording equipment is usually designed to work with balanced wiring. While XLRs are the most widely used connectors with balanced wiring, a particular connector does not guarantee the existence of balanced wiring. Some cameras and most professional sound recorders provided balanced XLR connectors for audio input. See unbalanced line.