A multi-platinum, Grammy-winning debut album buys an artist a lot of collaborative clout, and a lot of expectations to go with it. Welsh singer Duffy stacked the deck for Endlessly, the follow-up to 2008’s smash Rockferry, bringing in veteran British songwriter Albert Hammond to produce and co-write, and The Roots to serve as backing band. But their combined powers can’t rescue her from the fabled sophomore slump. Endlessly makes cautious stylistic moves away from the faithful blue-eyed-soul pastiche that characterized Rockferry, edging ever so slightly toward the dancier realms of Northern soul and even early disco. Clearly trying to replicate the huge radio success of Rockferry’s lone non-ballad, “Mercy,” Endlessly is much heavier on uptempo tracks than its predecessor. With the exception of the boisterous, catchy single “Well, Well, Well”—which elevates Duffy’s pinched vocals to even greater heights of love-it-or-hate-it-dom—most of these dance tracks come off as opportunistic trifles, particularly the “Papa Don’t Preach” retread “Keeping My Baby.” It’s interesting to see Duffy branching out, and her distinctive vocals often give these tracks a certain kitschy flair, but they don’t ring true. She returns to her favored milieu on the ballads, with generally solid results, such as the alone-on-prom-night weepie “Too Hurt To Dance” and the understated title track, which foregoes Duffy’s usual orchestral instrumentation in favor of a sparse acoustic guitar. Duffy is clearly striving for growth with Endlessly, but outside her comfort zone, she comes up short.