There is such a thing as being too perfect. Whitney Houston, whose brand of polished, platinum-plus pop-soul attracted sellout crowds at Merriweather Post Pavilion Saturday and Sunday, is a case in point.

Slim and chic in a spangled white mini-dress, the siren sifted swiftly through her treasure trove of flawless pop baubles. And there's the rub. Though Houston has a technical prowess almost unrivaled in current pop, with a luxuriant, lacquered tone that thrills when it hits those Big Notes, she has a reticent, nearly negligent stage persona, and she applies the same vocal technique, however impressive, to love-lost torch songs and upbeat dance tunes alike. In concert, the singer's immaculate soul was somewhat lacking in spirit.

Commendably avoiding rote repetition of the unbroken string of pop pearls culled from her two albums, Houston demonstrated unwavering control of pitch and power as she broke each hit out of its radio-required three-minute confines, stretching, restyling and refreshing songs that have grown overly familiar with endless airplay. "Do you remember this one?" Houston said, introducing "How Will I Know?" and "Saving All My Love for You." (Surely last summer's biggest hits can't be regarded as oldies so soon.)

Houston fared best with the ballads. On "Just the Lonely Talking Again," Houston sang as if she had all the time in the world, twisting notes sharply upward and letting them spiral slowly downward. There was also an appealingly kittenish cover of the Isley Brothers' "For the Love of You," which usually requires more simmer and sensuality; and the singer charged a forgettable song like "Where Do Broken Hearts Go?" with a series of gospel-styled shudders and crescendos. There were no fancy sets, no distracting props, just the singer, front and center, always tastefully avoiding unnecessary histrionics.

Unlike chart equal Madonna, who has burnished her appearance and her performance into an iconic image to justify her sales clout, Houston seems so far to have remained her shy, unspoiled self. Which is certainly commendable, but hardly exciting to see on stage.

Houston occasionally urged the crowd to dance, but except for stalking around the stage, she seldom moved herself. Clutching a pale pink handkerchief like a security blanket, she had to remind herself to smile once in a while, it seemed.

Houston did shake loose for a moment, and it was delightful to see -- during the conga break on "Love Will Save the Day," she relaxed and took a few coltish, unchoreographed steps. And there was a bit of fun with some pocket imitations of Janet Jackson, Anita Baker and Luther Vandross.

But these spoofs seemed as carefully scripted as the rest of the evening, and the closing number, "I Wanna Dance (With Somebody Who Loves Me)," which had the potential to be a spontaneous roof-raiser, was disappointingly lackluster. Part of this can be attributed to Houston's seven-piece band (plus three fine backup singers), which supplied crisp but colorless support on her pop confections, carefully staying out of Houston's way.

Houston was at her most impassioned on "a song my mama taught me," a gospel number called "I Believe," slowly building a simple bass-and-piano foundation into a fervent prayer that might have redeemed a few in the crowd.

Her other big moment was -- perhaps tellingly -- a love song to herself. Encoring with "The Greatest Love of All," Houston closed her eyes, and it was as if she were alone in her room, or in the recording studio.