The M-864D is a 4U rack mountable Digital stereo mixer having 8 monaural Mic/Line input channels and 7 stereo input channels, 6 output channels including 4 bus assignable monaural output channels and 1 stereo recording output channel. It is equipped with digital signal processing functions such as Automatic Resonance Control function (ARC(*1)), Feedback Suppressor function (FBS), Automatic stereo input mute function (AUTO MUTE or Ducker), and Equalizer. Advanced acoustic compensation can be automatically performed without using an acoustic measuring instruments. Furnished with various function setting buttons and 14 analog volume faders, the M-864D can be operated without the need or use of a PC. However, it can also be operated by connecting the PC or optional Remote control panel. It can be mounted in an EIA standard component rack (4U size).