Built-in compressor: Tighten your input signal for a puncher and more defined sound using the built-in compressor. It features both an on/off switch, as well as a variable gain knob. Main input: Plug in your bass using a standard 1/4in instrument cable. Headphone output: Plug in a pair of headphones to the headphone output to disable the speaker, so you can practice at any time, day or night, without disturbing the neighbors. XLR DI output: The built-in Direct Injection (D.I) XLR output makes it easy to connect to house PAs or mixers, while eliminating noise and making it easier to control the tone.