Golden Age Project COMP-54 Single-channel Vintage Style Compressor (USED)IN GOOD CONDITION, ONLY COMES WITH THE POWER SUPPLY. DOES HAVE A FEW SCRATCHES (SEE PICTURES). The COMP 54 is a one channel vintage style compressor. The signal path uses only discrete components like resistors, capacitors and transistors. The input and output are transformer balanced and the unit also uses a third interstage transformer. This is the way audio components were built before integrated circuits became available. ICs are small and cheap