How much better is Esoteric K-03 vs K-05?

Was about to pull trigger on K-05, but keep reading how incredible the K-03 is. This may be a function of less press/reviews/purchases of the K-05, but I really would like to know if the K-03 provides a small incremental improvement in SQ, or it's major. And if major, how so? If you've heard both, or know someone who has, can you please provide opinions and comments? Thanks much...