API 3124+ 4 Channel Preamp - the same microphone preamp circuit that is used in all API consoles, RE-115K mic transformer and output transformer. Channel controls: 48V phantom power, phase, pad (-20dB), mic/line. Font high-Z unbalanced input for guitar or bass (up to +22dB), output up to +30dBm, 65dB channel gain, XLR in/out (rear).