Historical clue formulations

• Speaker booster — 2019-10-08
• Audio engineer's device — 2019-08-04
• Roadie's tote — 2011-06-21
• Stereo component — 2009-08-27
• Signal enhancer — 2002-08-06
• Speaker booster — 2002-04-14
• Hi-fi component — 2000-11-23