Questions about Akai Professional AS110RA-320

The (active) subwoofer is connected to the small yellow jack output at the bottom left. But first a warning: I received this device and returned it because the background noise level is simply too high for home use. You can constantly hear a whispering noise that is very distracting (especially via Bluetooth). The device may be acceptable for loud karaoke in the cellar, but not for the parlour!