Source without a doubt. BUT all others add to the SQ. Without a source you don’t start with the tone of the instruments such as violin, stand-up bass, piano and sax. Those all have a unique sound that the other components cannot compensate for in our opinion as audio manufacturers of each of these components.
Best Stereo Upgrade Value
A question for you audiophiles...
What "upgrade/change" has singularly given you the biggest (not incremental) improvement to your stereo system? Upgraded amp, pre-amp, tubes, room correction unit, subs, connectors, cables, speakers, streamer, stylus, speaker placement, acoustic panels, etc.?