What is Good Sound? And, How can you tell the difference?

One of the questions that I get asked very often, especially from beginners who are just starting into the hobby of listening to music, and I mean seriously listening to music on good-sounding headphones and speakers, is what is the definition of good sound? How can you measure good sound and objectively know when one piece of equipment sounds better than another? I’m going to try and talk about this a bit in my video and share my understanding.