The Si Expression 1 Features 16 Faders, 16 Recallable Mic Pre Amps Plus 4 Line Inputs, 4 Internal Stereo FX Returns, AES In, And A 64x64 Expansion Slot Offering More Than Enough Scope To Use Every One Of The 66 Input Processing Channels. The Si Expression 1 Can Be Rackmounted With The Included Rack Ears.