The stained glass backdrop of the Maintenance Shop stage has cast its glow on thousands of musical acts in the venue’s near 30-year history. But there is only one pair of musicians who can claim to have performed before the trademark windows at least once during every one of those years.

Robin and Linda Williams will bring their marriage-inspired brand of folk and bluegrass, along with the couple’s appropriately named Their Fine Group, back to the M-Shop on Wednesday.

Linda says she and Robin have a special relationship with the venue they’ve been with since the beginning, and since most clubs don’t last nearly as long as the M-Shop, this is an opportunity many artists don’t have.

“The Maintenance Shop is a really special place,” Linda says. “There aren’t that many clubs that get that kind of really interesting caliber and cross-section of musicians like the Maintenance Shop does.”

M-Shop coordinator Eric Yarwood says the Williamses are invited back each year because there is always a steady and receptive audience ready to see these “sweet people” in concert.

“The fact that these two have been touring for 30 years together, and married and together all the time, you can tell,” Yarwood says. “They finish each other’s sentences when they’re across the room from each other.”

The four-piece lineup of Their Fine Group has been an integral part of the Williamses music for much of the duo’s career. Robin plays guitar and harmonica, Linda plays guitar and banjo and the pair sing together on most of their songs. The group also features bassist and backup singer Jim Watson, who has been with Robin and Linda since the group’s formation in 1988, and mandolin player Jimmy Gaudreau, who joined the band two years ago.

Linda says this variety of talented instrumentalists gives Robin and her the freedom to produce a very individual sound.

“The music itself has a good bounce, a good hard driving rhythm,” Linda says. “It can also be quite tender, so there’s a good variety of music.”

Linda says the group has had a following since its beginning, but has seen a noticeable resurgence in popularity after the release of the bluegrass-filled film, “O Brother, Where Art Thou?”

“We’ve had a steady growth,” Linda says. “We just have a little grassroots swell, and it just continues.”

Linda describes her music as a mix of country, bluegrass and folk.

“The sounds are pretty lyric driven as opposed to rhythmic,” she says. “They’re sort of story songs.

“It’s the music of the people and everyday life. Life from a personal point of view.”

The Williamses’ music has been featured on National Public Radio’s “A Prairie Home Companion” since 1975. The duo has also recently released their 16th album, “Visions of Love.” Although their past albums have mostly showcased original songs by the Williamses’, the songs featured on their latest release are remakes of old classics, such as Hank Williams’ “Ramblin’ Man.”

“It just focuses on people that we’ve been inspired by,” Linda says.

After playing music together for nearly 30 years, Eric says the duo’s music speaks for itself.

“It’s one of those bands,” Eric says. “You listen to it the first time and you enjoy it — you listen to it a second time and you’re addicted.”

Who: Robin and Linda Williams

Where: M-Shop

When:7:30 p.m. Wednesday

Cost: $7 students $10 public