The agreement came on the eve of ABT's spring season at the Metropolitan Opera House, which begins with a gala concert tonight. According to press reports, musicians authorized a strike over the weekend and were prepared to walk out over pay and the Sinfonia issue.

"We are pleased that the American Ballet Theatre has agreed to uphold its commitment to live music by agreeing to ban the use of any virtual orchestra machine at Lincoln Center or any place else in New York City— the live music capital of the world," said David Lennon, president of Local 802.

Rachel S. Moore, executive director of ABT, said, "ABT is committed to the use of live music and we are pleased that the musicians will be on board for the opening of our Metropolitan Opera House season."

There was no indication that ABT planned to use the Sinfonia, but Local 802 has demanded a ban on the device in all of its contracts since clashing with the Opera Company of Brooklyn over its use in 2003 and 2004.

The Sinfonia, which is leased to performing groups by Realtime Music Solutions, uses a series of recorded samples to simulate an orchestral performance. According to the company, the machine allows a live performer to control tempo and other subtleties.