The Datavideo AM-100 is a 1U high rack and 5 channel Audio Mixer and can be used with the SE-900 in OB Vans, etc.

1U 19" rackmountable professional audio mixer
Ultra compact 4 input + 2 AUX mixer featuring low noise,high-headroom design
Four studio-grade Dynamic Range mic preamps with:
Ultra –wide 60dB gain range
130dB dynamic range
+22dBu line input handling
Extended low-frequency response
Distortion under 0.0007% (20Hz~20KHz)
Phantom power for studio condenser mics
Six high-headroom line inputs
Advanced DC pulse transformer RF rejection
18 dB/ octave, 100Hz low-cut filter on mic input channels
High resolution 8 segment stereo meters
Supports both Line or Microphone with 48v Phantom power
Fifth auxiliary channel can be used as line or for daisy chaining with other AM-100 (upto 12 channels)
When used with SE-900 & MS-900 the AM-100 provides synchronized audio follow video using a 15-pin D-Sub connection