Related Clues:

• Guitarist's aid
• Intensify, with up
• Increases the volume
• Intensify, with "up"
• Concert piece?
• Rock band's accessory
• Roadie's loads
• Crank (up)
• Energizes, with "up"
• Rock band booster
• Sound investment for a band
• Big concert equipment
• Roadie's burden, in part
• One for the roadie
• Increase, with "up"