I have heard the 2 side by side playing one jazz piece over and over again with the same IC/amp/preamp/speakers. the difference between them was very hard to distinguish. The 588 to my ear, is the winner, however, both players display a very lifelike presentation of the original recording. It is possible that if you play different types of music you may find the 507 more to you liking and vice versa. At almost double the cost, only your ear can decide if the 588 is worth it. Given the difference in price tags, and the minute differences I heard, I would personally go for the 507 and be completely satisfied with my purchase. Most Meridian dealers will have both on display and you should at the very least hear them side by side in the store, then take them home and listen in your system.