'Homeless Mozart' David Allen Welsh has rare musical gift - moves listeners to tears in thrift shop...

A homeless man who says he cannot read music and has had no formal musical training has stunned staff and customers at a Vancouver second hand store with his virtuoso piano playing.

With severely frostbitten fingers from years of living in the cold, David Allen Welsh, 50, pounds out spontaneous almost classical sounding performances on an old piano at Second Hand Solutions, a thrift store and coffee shop run by Open House Ministries.

Staff at the store say Welsh, who has been homeless since he was 6, has been coming in once or twice a month for at least a year, each time impressing customers with his piano improvisations, even moving them to tears.

"It's amazing it's really beautiful," says assistant manager Rebecca Gore. "I showed a video of him playing to a piano teacher and she pointed out immediately that he's using his left hand as a primary and his right hand to play the melody."

Welsh says he has no control over his playing and that it's as if the music takes hold of him. He's never taken a piano lesson and can't read a note.

"I don't know how to play music, but I like what I hear in my head," he told ABC News affiliate KATU. "Sometimes I don't even know what key I'm pushing. My eyes aren't even open. I'm just letting the music play the music."

Gore says often people will come into the store and have a go on the piano, but that Welsh's playing is truly spectacular. She is especially impressed considering the damage to his fingers which are numb and purple.

One customer, James Maynard, who lives next door and regularly comes in to the shop for coffee, welled up with emotion when he heard Welsh play for the first time, saying he had never heard anything like it.

"He started to play and I choked on my coffee and it started coming out of my nose," Maynard, who is a longtime classical music enthusiast, told ABC News."I had tears coming to my eyes when I saw his fingers go down one end of the piano to the other."

Welsh was born in Iowa and raised in the Dakotas where rode around on trains for a while, he told KATU. He discovered his gift at an early age, but has only been able to play on borrowed pianos at different homeless shelters and stores throughout the Pacific Northwest where he moved more than a decade ago.

Welsh says sharing his music has kept him going through tough times, and that it's as if his fingers are moved by a divine power.

"My custom is to sit and close my eyes and say, 'Dad, do what you do, it's your gift'," Welsh says. The grateful recipients of Welsh's playing agree.

"It was like the holy spirit came through the building," says Maynard. "It's a joy that surpasses all understanding, that's what I felt. A lot of people in the room had the same spiritual experience."