Question I want to prevent the dust damaging my cabinets for my bass amp, can I block the holes behind the cabinet Answer The holes in the back of your cabinet are tuning ports. These holes are an integral part of how the cabinet operates and they allow it to reproduce the bass frequencies they way you hear them. Blocking these ports will change the sound of the cabinet, so if you do decide to put anything like foam in them for example, just be aware on the sonic differences when doing so.