About Speakon Connectors :

The Speakon is a type of cable connector, originally manufactured by Neutrik, mostly used in professional audio systems for connecting speakers to amplifers.

A Speakon connector is designed with a locking system that may be designed for soldered or screw-type connections. Line connectors (female) mate with (male) panel connectors and typically a cable will have identical connectors at both ends. If it is needed to join cables, a coupler can be used (which essentially consists of two panel connectors mounted on the ends of a plastic tube)

Speakon connectors are made in two, four and eight-pole configurations. The two-pole line connector will mate with the four-pole panel connector, connecting to +1 and −1; but the reverse combination will not work. The eight-pole connector is physically larger to accommodate the extra poles. The four-pole connector is the most common at least from the availability of ready-made leads, as it allows for things like Bi-Amping (two of the four connections for the higher-frequency signal, with the other two for the lower-frequency signal) without two separate cables. Similarly, the eight-pole connector could be used for Tri-amping (two poles each for low, mid and high frequencies with two unused).