May i ask why, specifically, Rick Rubin? I don't know who that is, but whenever we finished mastering a new song, we had a series of "systems" we listened to it on. We went out to my dad's work van and listened there. We called up our friend with a street-comp sound system in his car, and listened in there (neighbors must have loved us!), and then a "cheap" boombox with large-ish speakers but cheap.

if it sounded "clean" on all 3, without the bass muffling everything, and the highs not hurting the eardrums, we called it "good" and released.