The IFB-104 is a 1RU panel that directly connects up to four IFB feeds to the ports of a digital matrix system. Individual or multiple IFB ear buds or headphones may be used directly from each connected matrix port. The IFB-104 does not require external power to drive its circuitry. Each channel has a rear-mounted wet/dry switch, allowing either direct connection or powering via a party-line intercom power supply. The signal from the matrix port is transformer-coupled to the XLR connector output.