Kicker ZXSUM8 8 Channel Summing Interface with Aux Sums up to four speaker-level stereo pairs down to a single stereo RCA low-level output. Each stereo channel is capable of both summing and line-output conversion; switched internally. Integrate portable media direct to your amp using aux-in and level control. 4 stereo speaker-level inputs. 4 line-level stereo RCA outputs. Multi-function remote controls both the aux-input level and the Channel-4 output to separately adjust bass and aux levels from the same remote source. Balance levels from multiple speaker-level sources.