At almost any time of the day, it's more than likely that music is playing in the home of Michael and Deborah Charness.

As early as 7 a.m., Daniel Charness, 10, is up and practicing his cello. As late as 2 a.m., Michael Charness, a doctor, is still awake playing his piano. During the day, Deborah Charness may catch a chance to practice her flute when she's not teaching young musicians or shuttling the three children to their various daily activities. In the afternoons and evenings the two girls, Sarah, 12, or Jenny, 7, fill the house with violin music.

On a daily basis, each family member practices separately. But as often as they can, the five musicians come together in their Waban home to rehearse the pieces they perform as The Charness Family Quintet.

The idea for a family act came six years ago when Michael and Deborah were performing at the Newton Free Library. In a moment of inspiration they invited Sarah, then age 6 and a budding violinist, to come on stage with them to perform a minuet. Daniel added his cello to the mix at age 5, spending months in preparation to join in for one musical number. Two years ago, Jenny joined to complete the quintet.

They attract far more attention as a family act than the couple did as a duo, and the children are now fully integrated into the performances of mostly classical music.

"Our last performance was an hour long, and my solo was two minutes. They all do solos," Deborah said.

The family still gives an occasional concert at the Newton Free Library, but they now get requests to perform throughout New England. On Sunday, the Charnesses will perform at the Cambridge Multicultural Arts Center. The family limits itself to two or three concerts a month. With all the other family activities it's hard even to schedule rehearsals, let alone performances.

"It's hard for us, believe it or not as a family, to find the time to rehearse together," Deborah said.

Deborah and Michael met through music, and have made music a part of their family life ever since.

"We met on a blind date. He wanted to meet a musician," Deborah recalls.

Deborah certainly fit the bill. She had studied flute in Paris, and in 1976 was selected by the American government for a concert tour of France as part of the Bicentennial celebrations.

The couple had been dating a short time when Deborah got a call to play at the Gardner Museum. She invited Michael to join her in the performance. They got engaged that evening, and agreed to maintain their partnership on stage as well as in life.

"He spent our whole honeymoon learning flute music," Deborah Charness said.

They spread their love of music to the three children, introducing them to an instrument as early as possible.

"These kids don't remember when they didn't play," said Deborah Charness.

Sarah chose her instrument after meeting a violinist who performed with her father when the family lived in San Francisco.

"She'd come over and play music with my dad. I just loved the violin. I loved everything about it. She gave me a toy violin. I would chew on the bow and pretend to play."

Daniel become interested in the cello during a family trip to a music store. Jenny simply chose the violin to be like her sister.

"I was a copy-catter," she said.

In addition to practicing every day, the two older kids find ways to fit in other activities. Sarah juggles dance and gymnastics and tutors the younger members of her temple as they prepare for their bat mitzvahs. She spends a full day, from 9 a.m. to 6 p.m., in music lessons each Saturday, with violin lessons in the morning, piano lessons in the early afternoon, followed by rehearsals with the New England Conservatory Youth Orchestra.

Daniel finds time for baseball and hockey, and next year, he wants to add another sport.

"I didn't play football this year, but I really want to," he said.

Both parents are as involved in their children's music education as they can be. Michael Charness, who was working when the rest of the family got together for an interview, is often up with Daniel for his early morning practice session, then spends the evening with Sarah for hers, which leaves only late night hours for the parents to get in their own practice time.

"When we practice, it has to be when [the kids] go to bed. Sarah didn't start until 10:15 last night, then she practiced until quarter of 11," said Deborah.

Sometimes at 1 or 2 in the morning, I still hear him waddling away at his piano," adds Sarah.