Steinway Musical Instruments, a 160-year-old maker of pianos, saxophones and trumpets, said it received a takeover offer from an investment firm it did not identify that topped a bid by private-equity firm Kohlberg & Co.
Steinway shares rose more than 8 percent on Monday, more than a dollar above the new offer price, indicating that some investors expected a higher offer.
The company said only that the new bidder managed more than $15 billion.
Steinway said in December that it had decided not to sell itself after a 17-month-long review of strategic options.
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Six months later Kohlberg made an offer of $35 per share, valuing the company at about $438 million. The latest offer values Steinway at about $477 million.
Steinway said on Monday its board had determined that the new offer was superior to Kohlberg's.
Kohlberg has the option to improve its offer.
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Steinway's pianos have been used by legendary artists such as Cole Porter and Sergei Rachmaninoff and by contemporary ones such as Chinese concert pianist Lang Lang.
But the Waltham, Massachusetts-based company's sales have been stagnating and it has struggled to keep production margins competitive. Sales rose just 2 percent in 2012