Christina Aguilera is an international superstar with millions in the bank, a reportedly blissful marriage, and a voice big and burly enough to send even Mariah Carey toppling head over Manolo Blahniks. But on her sprawling new double CD, Aguilera is seeking something more elusive: respectability. She's revamped or rather, de-vamped her look, sporting an Andrews Sister bouffant and jazz-age togs in the video for Back to Basics' first single, ''Ain't No Other Man.'' She's added saloon songs to her repertoire of ballads and club tracks, peppered her lyrics with shout-outs to jazz and blues greats like Billie Holiday and Etta James, and made no secret of the fact that she wants a place in that pantheon. ''I've waited for some time/To get inside the minds/Of every legend I've ever wanted to stand beside,'' she sings in the opening ''Intro (Back to Basics).''
Aguilera doesn't have the gravitas of her heroes, and her forays into bluesy torch singing and '40s-style swing are stiff and mannered. But she needn't genuflect before the past she can make her own glorious kind of 21st-century noise. CD 1 is helmed by DJ Premier (of '90s rap duo Gang Starr) and a host of other hip-hop producers, and their rugged dance tracks, mixing electronic beats with honking brass and other '70s soul samples, are perfectly suited to Aguilera's powerhouse belting. The gospel testimonial ''Makes Me Wanna Pray'' features a torrid vocal by Aguilera and some warm Hammond B-3 organ work by Steve Winwood, and ''Slow Down Baby'' neatly blends old- and new-school R&B, with samples of both Gladys Knight and rapper Tony Yayo. Many songs are dedicated to Jordan Bratman, Aguilera's husband of nearly a year, but even in her most lovey moments, she's still a diva. The exhilarating ''Ain't No Other Man'' whizzes past at such a furious pace, you might miss the threats that mingle with pledges of devotion: ''So tell your mother, your brother.../Tell the others, your lovers/Better not be present tense/'Cause I want everyone to know that you are mine and no one else's.''
The second disc a collaboration with Linda Perry, the writer-producer behind Aguilera's 2002 schlock-pop masterpiece ''Beautiful'' ratchets up the bombast. Few singers would dare attempt a song like the rock-tinged ''Hurt,'' whose self-help bromides Aguilera delivers with melodrama that would make Barbra Streisand shudder; fewer still could make it so compelling. Then there's ''The Right Man,'' a well-nigh Wagnerian ballad about Aguilera's wedding, in which she blasts out unearthly melismata over crescendos from a 27-piece orchestra and a full choir. Respectable? God, no. But definitely worthy of respect.