Conductor Maxim Shostakovich, son of the Russian composer, stood in the Kennedy Center's Golden Circle reception room, almost quivering with emotion.

"At first it was a strange feeling," he said, "seeing someone on the stage playing my father. But then, after a few minutes, he looked and moved like my father. I was so affected, I wanted to protect him. It is a very deep, angry play -- how the ugly, stupid great powers torture the sons of the people."

Shostakovich and Michael Zaslow, who plays the composer in "Master Class" (an imaginary confrontation between Dmitri Shostakovich, Sergei Prokofiev, Joseph Stalin and cultural czar Marshal Andrei Zhdanov), drank toasts to each other at the supper after Sunday night's preview in the Eisenhower Theater. Only one problem, Shostakovich took Zaslow aside to explain -- the composer didn't wear a handkerchief in his coat pocket.

"Thank God, I didn't know Shostakovich was in the audience until after the show," Zaslow said excitedly. "I wasn't sure about the handkerchief. I didn't think he'd wear a wedding ring, and his son said he didn't. Of course, from now on I won't use the handkerchief either."

"I cried," said Galina Vishnevskaya, all shimmering sequins, as she arrived at the party with Shostakovich. "The play, the people, were all true. Good performance, good acting. Good production." Vishnevskaya's autobiography of her life as a Russian diva, published to rousing applause, is full of stories of Russian cultural figures.

Playwright David Pownall said Prokofiev's widow and son came to the London opening to see the composer portrayed. Of writing the role of Stalin, Pownall said, "You can't do a play unless you make him not the political monster everyone knows, but something more -- a man both good and bad."

As to there being a trend toward plays about musicians, the playwright said this is his second (his first was "Music to Murder By"). "Music is free. Totalitarians can't control it, though they'd like to. Music is very frustrating to totalitarians."

George Dzundza, who plays Stalin, sampled the champagne but none of the delicious chicken Kiev. "It's a demanding part," he said, "but the job of doing the play overrides the work." Learning to keep his left arm immobilized took much concentration, he said, "but now I don't have to think about it."

Zaslow studied Shostakovich's memoir, "Testimony," and music in preparation for the role, he said. "Before the play, we were more traditionalists -- Bach and Mozart. I studied to be a concert pianist but gave up on it. I did work as a cocktail pianist and had my own rock 'n' roll band. I write songs, too."

Werner Klemperer, the son of conductor Otto Klemperer, plays Prokofiev. On his way to the lavish Russian buffet, Klemperer said he indeed plays the piano, but had to practice for the piano episodes in the play.

Dick Latessa, Marshal Zhdanov in the play, sat by conservationist Christine Stevens at the supper table. Replying to congratulations on the Russian dance he performs in the play, Latessa said he "started as a dancer, briefly. Dancers have the shortest careers." As for his sword-down-the-back military bearing, he explained, "I was in the Army. Wasn't everybody?" He described the four-man cast as "very sensitive, though we all border on the insane. Some of the things we've learned about each other are not fit to print."

Former undersecretary of state George Ball said that he had not met Stalin. "He was before my time -- though I've heard stories. I thought the play was an extraordinary, interesting study."

On politics closer to home, former head of the National Endowment for the Arts Livingston Biddle, at the party with his wife Catharina, said that he's "put aside the two books I'm writing until after the election. For now, I'm working to mobilize artists for Mondale."

The Istomins, conductor Eugene and Kennedy Center artistic director Marta, sharing one chair in the supper room, served as unofficial translators for Shostakovich from time to time.

The play's company and other theatrical types stayed on long after the usual 11 p.m. party curfew for most of the evening's 100 guests, who have jobs that begin at 8 a.m. instead of 8 p.m.