The 4 contact configuration (+1, -1, +2, -2) allows the user ultimate freedom in customizing the connectors to their specific setup. The standard contact configuration allows the user to run two speakers in full range (speaker one on +1, -1 and speaker two on +2, -2) or a single speaker in a bi-amp configuration (low frequency driver on +1, -1 and high frequency driver on +2, -2).