There are many bands of limit range functions. 
 1>.  Balanced  professional cannon plug dual channels input and  four channels output, and it can be setting as  bass output. 
2>.  Every channel can be set up the constringent setting  independently and  change to all－band or two-way output. 

3>.  Every channel have three output mode: balanced, unbalancedand BTL. 
4>. Auto safely  limit the input big signal, it is insure that the back amplifier can be balanced output and avoid mangling the speakers. 
5..  Insert bass switch can switch to plus control. (Ch1/ Ch3).

6>.  Low  frequency output can output independently, it also can dual channel mixed output, swell the convulsed volume of low frequency. 
7>. LED show  all channel constringent state.

Specifications:

General harmonic distortion.................less than 0.16% 1KHz
Frequency response (music's signal)....40Hz～20KHz+3dB   (A standard)                     
Output impedance.................................51Ω
nput impedance.....................................(Unbalanced)
Dynamic range.......................................105dB
Signal-to-Noise.......................................more than 70dB (A standard)
Separation..............................................57dB
Consumed power....................................10W