I went from an X350 to an Edge NL-12. The Pass's bass was more oppressive and much less nuanced than the Edge. The Edge's bass has more dexterity and is more natural, deep but not pushy. The Pass is slightly more silky on voices, but barely so, but the Edge has more air and again sounds more natural. In fact, I would say that the Edge's greatest strength is the airiness of all musical components, and the ability to place these components in their own space. The Pass has more of a golden glow that can be very appealing on lesser-quality recordings, while the Edge will show the flaws in these recordings. The Edge is more open and relaxing. The Edge portrays complex orchestral passages with ease and no sense of compression. The Pass was slightly compressed. The Pass ran very hot & would heat up the room so much it left me sweating. Both the Pass & the Edge have smooth, not-tizzy highs. The Edge is never more than warm. I am very happy with the Edge. I heard my Kharma speakers with good tube amps and I prefer the Edge, which has a feeling of purity. Perhaps it would be more fair to compare the X600 to the NL12, but I never did hear the 600s. 'hope this helps.
