The 3S framework reminds us that no single element determines audio quality. A perfect source played on a poor system in a bad room sounds poor. A mediocre source on a great system in a treated room can sound excellent. Optimizing all three is the goal.
Practical hierarchy for improvement: 1) Space (room treatment, speaker placement) — the most neglected and most impactful, 2) System (speakers, amplification, DAC) — where most budget should go, 3) Source (high-quality recordings, lossless formats) — only matters once space and system are adequate.