Ms. Jones is also an example of the cross-pollination between the two businesses: In addition to performing at the Living Room, she has recorded at the Magic Shop, most recently for a 2013 album of Everly Brothers covers she did with Billie Joe Armstrong of Green Day. Sometimes Mr. Rosenthal records new musicians from the club “on spec” — which often means free. “Maybe that’s not smart business,” he said. “But it’s good art.”

The Living Room moved around the corner to Ludlow Street in 2003, and then last year, after being priced out of Manhattan, it relocated to Williamsburg, Brooklyn. The venue is spacious, but business so far has been light.

Straitened finances mean fewer employees to help share the load, and Ms. Gilson and Mr. Rosenthal, who live in Chelsea with their three young children, described a frenzied joint workday: Rising at 6:30 a.m. to get the children out the door and deal with a barrage of “you owe me money” emails, and then shuttling between the Magic Shop and the Living Room for the rest of the day and much of the night. Occasionally, Ms. Gilson said, she slips away from the bar to put the children to bed via FaceTime.

“There’s no room for failure anymore,” said Ms. Gilson, who started out as a waitress and talent booker at Sin-é, the East Village boîte known for giving an early stage to Jeff Buckley. “For art to succeed there has to be room for peaks and valleys, but it’s all about paying the bills here. There’s no way to just try something out over the next few months, see if it will work.”

To stabilize both businesses, Mr. Rosenthal tried to buy the two floors the Magic Shop occupies in its building, with help from Mr. Grohl. In December 2014, just as the Magic Shop’s episode of “Sonic Highways” was broadcast, Mr. Grohl lent the studio $50,000 to help cover its back rent, and he agreed to finance Mr. Rosenthal’s attempt this spring to exercise a purchase option on the studio’s lease, for just less than $3 million.