Historical clue formulations

• Casual musical project — 2026-04-07
• Forerunner of a streaming playlist — 2024-05-11
• Collection of favorites, of a sort — 2017-08-05
• Personal music compilation — 2015-10-20
• Homemade music compilation ... or a hint to the circled letters — 2011-06-27
• This-and-that recording for a friend or a party — 2007-08-17