Broadway producers say they will use "virtual orchestras" to replace union musicians if they go on strike.
Strikes are due to begin on Sunday
Some 19 Broadway musicals will be running when strikes are due to begin on Sunday.
The American Federation of Musicians plans to pull its members out to protest against proposed cutbacks.
"Every show will be prepared in one way or another with music in the event of a work stoppage," said Jed Bernstein, president of the League of American Theatres and Producers.
Almost all the musicals affected are holding or will hold cast rehearsals this week using electronic equipment instead of live performers.
There is no intention to end live music on Broadway
Jed Bernstein, The League of American Theatres and Producers
The union says a proposed reduction in the number of musicians is an attack on live music.
"Performing in front of a full orchestra is nothing short of amazing," said Tony winner Audra McDonald, in a radio commercial for the union.
"I know music and I know how live music sounds and feels," she added.
"I can't imagine singing to a computer-generated sound."
The negotiations have so far focused mostly how many musicians are needed to play for a show.
Producers say the current minimums - which are determined by the size of a theatre - are requiring them to use more musicians than are needed.
"There is no intention to end live music on Broadway," said Bernstein.
"Live music is indigenous to Broadway. It is fundamental and it is vital and it isn't going away.
"The only thing that could possibly disrupt the performance of live music is if the musicians' union decides to go on strike."
Union president William Moriarity has scheduled a strike vote for Saturday.
"We intend to negotiate," he said.
"We hope to negotiate. I think we would have to have a good reason to walk."