Strange Input on my AMP

[Cxrazy]

I have an older MTX 300w amp that I have running my subwoofers.

On the amp there is a phone jack looking thing that I suspect can be used with a type of control knob. A mass amount of googleing, and looking around and I have yet to find out what this is for.

Any ideas?

 

[Perry Babin]

It's a remote level control. The owner's manual may be available on the MTX site.