Benchmark IFA -4 Amplifier IFA-1 Interface amp PS-11 Power Supply Module Bundle. This product data sheet is originally written in English. IFA -4 Two Channel Line Amplifier.These charges are the buyers responsibility. Any product you return must be in the same condition you received it and in the original packaging. IFA -4 Two Channel Line Amplifier IFA-1 Stereo Interface amplifier PS-11 Power Supply Module Rackmount System All Tested.