The PS1A provides switching and monitoring control for up to four stereo devices. Easy comparison of input and output of any recording medium. This unit provides a variable level monitor output and two additional fixed outputs for metering, cue feed or master record path (ie; DAT, CD-R, or even linear magnetic media, aka... tape!). The mono switch allows you to check phase compatibility of a stereo source and only feeds the monitor ouput. All connections are via XLR.