IMO, the key is regular lubing. I shoot for about every 100 miles and after every wet ride (I lube the derailleurs at the same time). What I think works is that you keep a reservoir of lube in amongst the inner parts of the chain. As you ride, that oil works its way out and sloughs off, taking some grit and grime with it. Since the oil is working its way out, it needs to be regularly replenished.
As a result, I can only just barely hear my chain on smooth road (can't hear it at all if there's much texture to the road), and I intend to keep it that way.