The brother duos of early hillbilly music (e.g., Monroes, Delmores), mid-century country (Louvins, Everlys) and bluegrass (Jim & Jesse, Osbornes, Stanleys) have been much celebrated, and deservedly so. Husband-and-wife duos are less discussed, in good part because for much of the history of commercial white roots music women tended to be secondary figures, if that. Still, those of us with long memories will recall Lulu Belle & Scotty Wiseman, Wilma Lee & Stoney Cooper and, less famously, Harry & Jeanie West, New Yorkers transplanted from Virginia and North Carolina and carriers of authentic Appalachia in the nascent Village folk revival. (The Wests' classic Smoky Mountain Ballads, released in 1958 and reissued in CD in 2007, is well worth seeking out.)

In bluegrass, women have become far more prominent than they were in the genre's formative years, which may be why husband/wife outfits are so little remarked upon these days even as they're delivering stirring harmonies and fashioning soulful music. The Aldridges and the Slaughters have released a couple of satisfying albums in the past months.

Guitarist/songwriter/vocalist Shannon Slaughter is a veteran who's served time as a sideman with notable outfits including the Larry Stephenson Band, Melonie Cannon, Lost & Found, and Lou Reid & Carolina. Never Just a Song is his second solo album with Heather, though the first I've heard. It opens impressively with the traditional "Moonshiner," driven by Randy Kohrs' dobro and Ron Stewart's fiddle, supporting Heather's take-charge singing. It's the one nod to the old mountain music that preceded bluegrass; otherwise, the non-bluegrass influences come out of Nashville country. The second cut, Tim Stafford & Pam Tillis's "Never Just a Song," an appreciative but bracingly dry-eyed tribute, recalls the late, troubled country songwriter Harley Allen (son of longtime bluegrass band leader Red Allen). Sample lyrics: "He gave Jim Beam a bad name ... He could be more cruel than kind." If bluegrass, like country, can be pious in the worst sense, the Slaughters aren't afraid to be tough and honest.

Of course, there are passing moments of mawkishness (the original "That's What's Good in America"), but sheer musicality gets the couple through. The Slaughters aren't exactly a traditional band, though tradition is honored in their core sound along with more contemporary elements. Bill Castle & Shannon's "There Ain't No Need to Be Lonely," drawn from bluegrass's deepest emotional well, takes its inspiration from some of the most accomplished songs in the genre. There's also the unvarnished country of "Whiskey Colored Dreams," with Heather's believably resigned vocal sighing a honkytonk widow's lament while Tim Crouch's triple fiddles and Doug Jernigan's pedal steel supply the emphasis. A thrilling sound indeed. It may not be bluegrass, but it's pretty damn good, the sort of thing some Nashville star would pick up on if there were still country music in Nashville.

I haven't heard the original of Hank Williams Jr.'s "Feelin' Better" -- Hank Jr.'s records are not on my playlist -- but miraculously, the Slaughters manage to transform it into credible bluegrass song, even if they can't overcome Hank Jr.'s insufferably self-referential subject matter. Then again, who could? His father could take personal experience and render it universally embraceable, whereas with his son, self-absorbed even by entertainment-industry standards, the focus is always squarely, exclusively on himself.

It's certainly unfair to characterize the Slaughters as softies, but the Aldridges show a consistently harder edge on their excellent Snapshots, their sixth album together. There's also only one original song (the gospel "Will You Be Ready?" -- a co-write by Darin and the late Bobby Jones). The couple sparkle on Gillian Welch's "Annabelle," a marvel of narrative concision which takes on a big subject in the words and melody of an Appalachian-style ballad. They turn the Bill Monroe chestnut "Rose of Old Kentucky" into a conversation, not (as in the original) a monologue about a distant lover, in a way that subtly expands the song's meaning. Just as fearlessly, their interpretation transforms "Let It Be Me" (a 1960 hit for the Everly Brothers, originally a French pop song) from schmaltz into a near epic of erotic longing.

Brooke's singing is characterized not only by its pureness but by its versatility, alternately playful, sorrowful and worshipful. Though the song is a bit tired from over-exposure, Johnny Cash's "Tennessee Flat Top Box" induces a pleasant glow in Brooke's good-natured handling. Her and Darin's harmonies are especially sweet on the tuneful "Wait Till the Clouds Roll By." Though credited here to Uncle Dave Macon, it is in fact an English music hall song from the 1880s.

Either or both of these discs will enhance the quality of your music collection. As the sounds fade from the player, one looks forward to more and maybe even better from these quarters in days and years to come.