> Professional audio engineers operate out of carefully calibrated rooms designed to eradicate odd resonances and echoes, and their speakers cost more than your car.

That is not exactly true. I've seen many pictures from studios and most engineers use professional speakers (called studio monitors) in the $5K range.

However you can spend a lot more on acoustic treatments, they make a massive difference.

I like to think that color-grading, another mysterious dark art (to me at least), is the visual equivalent of mastering.