Devices:

    Mic: Behringer XM8500
    2nd input: e.g. iPhone
    Mixer: Behringer 502
    Powered speaker: Mackie CR3

Cabling:

    Mic to mixer: XLR female to male, connect mic to “MIC” of 502
    2nd input to mixer: 3.5mm to RCA male, connect (e.g. iPhone) to “2-TRACK”-“INPUT” of 502
    Mixer to speaker: RCA male to male, connect “2-TRACK”-“OUTPUT” of 502 to RCA input of CR3

Adjusting:

    Press down “2-TR TO MIX” button of 502
    Use “MAIN MIX” to adjust output level