Related Clues:

• Intensifies, with 'up'
• Fab Four equipment
• Stereo components
• Pumps up the volume
• Band boosters
• ___ up (energizes)
• Concert blasters
• Increases, with 'up'
• Rock boosters
• Rock gear
• Concert gadgets
• Enlivens (with "up")
• Sound boosters
• Units of current
• Sound projectors?