It's all about ear training! I couldn't tune a guitar by ear at one point but now know how out of tune a guitar is by ear, and know if their string is sharp or

It's all about ear training! I couldn't tune a guitar by ear at one point but now know how out of tune a guitar is by ear, and know if their string is sharp or flat (it helps to remember a song in that key and replay that note in your head compared to what you're hearing). The same is true of audio quality. I thought 128kbps MP3s were fine for years (I even had some MP2s somewhere) but now they sound like sludge.