When I moved from Sasha to S5, there were improvements across most sonic attributes. However, the area that impressed me most was the bass which to me is better defined, has richer tonal texture, and integrates with the upper range more coherently, not to mention faster bass transients and lack of overhang. It is most enjoyable listening to bass rich material. The sealed enclosure also seem to make it easier to place. Martin Colloms described the bass of the S5 quite accurately in his review:
http://www.absolutesounds.com/pdf/ma...20_OCT-DEC.pdf