API Audio The Channel Strip - combines many well-known and highly coveted pieces in one package: 512C mic pre, 550A EQ, 527 compressor and 325 line driver. Each processing piece can be switched in or bypassed individually and a flip switch allows the compressor to be placed after the EQ if desired. Additionally, the Channel Strip includes an insert point, sidechain input, multiple metering locations as well as the famous API 2520/transformer combination.