A guitar speaker isolation cabinet is a sound-proof enclosure that surrounds the speaker and sound-capturing microphone and prevents sound leakage into the outside environment, enabling the amplifier to be turned up without excessive listening volume. 

An amplifier at full volume is extremely loud, posing a risk to hearing and an annoyance to neighbors, and will often drown out other instruments in a mix .

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The characteristic sound of a tube guitar amplifier as heard on the majority of professional recordings is achieved by playing the amplifier at high volumes, and using one or more microphones to capture the sound. 

Turning the volume up causes the pre-amplifier to drive the power amplifier into distortion and the loudspeaker to "break up", adding distortion to the amplified tone. 

The speaker cone also generates more sound pressure , delivering more dynamic range and detail to the microphone.