Sitting on a table in the basement of the Washington Ballet School last week, resident choreographer Choo San Goh was quietly going over last-minute costuming details for his new ballet, "Schubert Symphony," which premiered at Lisner Auditorium last night. Clad in reversed red sweat shirt and green army pants, he looked thinner (if possible) than usual. He had just made it through another year of Washington responsibilities and farming himself out as teacher and dance designer to the Boston Ballet, the Joffrey Ballet, the Berlin Ballet and the Royal Danish Ballet.

"Look -- flowers in one of my ballets," he says, adjusting dancer Julie Miles' headpiece. "Can you believe it? I just think their jaws are gonna drop when they see this ballet."

How is it different? "Julie is the one to ask," Goh says, and Miles' eyes light up. "Oh, it is . . . it's a lot more free," she says. "I think it's sort of a follow-up to his 'Romeo and Juliet' Goh's first full-length ballet, created for the Boston Ballet . His other dances have strict themes you must follow. This one has just steps -- a lot of dancing all over the place. It's really fun."

Inspired by Schubert's Symphony #2 in B Minor, the dance is adorned with cavalier costumes in shades of pink, purple and gray. "The music got to me back in 1978, but I didn't dare do it then," Goh says. "I wanted to get more comfortable in the classical idiom . . . I expected difficulties and hard work in creating the dance, but it flowed much more easily than I thought -- I got a lot of joy from it. Yes, I think it's a mature piece. I think I'm ready for it."

Reviewers have described Goh's dances as angular, athletic, streamlined, exuberant, Asian flavored, intricate and sumptuously romantic. They claim that he is intensely musical, obeying the classical rules but doing so in a refreshingly contemporary form. It seems now, though, that the image of intense and sleekly unitarded dances is exactly what Goh is trying to break out of.

"I hate to be put in a box," he scowls, then says of his latest work, "I think it will open doors for me -- I don't know what kind yet, but it will change people's opinion of me."

Goh's relationship with the Washington Ballet began in 1976, when director Mary Day gave him a chance, sight unseen. Clint Farha, a friend and former student of Day's, now dancing with the Dutch National Ballet, had suggested that she consider the young choreographer.

"I respect Clint's opinion," Day explains. "He's loyal to the school and he knows I'm always looking for new talent. All he said to me was, 'I enjoy dancing Goh's ballets more than anybody's.' So I sent for him."

Day, Goh's colleague for 20 weeks a year, has a reputation for nurturing talent only to watch it leave for bigger and better things -- witness the careers of Shirley MacLaine, Amanda McKerrow and, most recently, Bonnie Moore. The annual question put to Goh is, will he be next? His annual answer is usually, "Everything is a possibility."

Matthew Diamond, a new choreographer on the horizon who has done work for television and Broadway, had a two-week stint with the Washington Ballet while Goh was gone in September. The company also performed one of Diamond's ballets in its fall concert and in Baltimore last week. Does Goh worry about the competition?

"Well, that's life, isn't it?" he answers. "I don't own this position. If they found someone to take my place and asked me to leave, that would be their prerogative and my problem, wouldn't it?" He's not being flip, but realistic. He's not really aloof either, just careful. When Miles is asked about the differences in dancing Goh's and Diamond's ballets, he tells her, "Avoid those kinds of questions."

Upstairs at rehearsal, his company waits to respond to his every terpsichorean thought. His fingers travel along his chin as he sings the introductions and cues when the tape doesn't. He has a good rapport with his dancers, and is comfortable adapting to most types of students in most types of places. He compares his recent homes.

"I had a very good experience this last time in Copenhagen," Goh says. "I was very 'up' there. Boston is very charming. The whole structure of the city makes it very relaxing just to walk through. It's very European -- a lot like Amsterdam. Washington reminds me of Paris. I guess it's very green, too, but to be truthful, my life here is so hectic I don't really get a chance to enjoy the city. I think the population is mostly made up of students and professionals. It doesn't cover as wide a span as, say, New York."

He is prodded about being more famous in other lands than in Washington. "I'm famous here," he says. "That doesn't mean people have to stop me on the street. Ballet just doesn't have that big of an audience."

In what country is he most famous? "Oh, I don't know -- maybe Singapore. I'm their golden boy," he says with a twinkle in his eye.

And what of the future? "I talked with Peter Schaufuss with the London Festival Ballet when I was in Europe a few weeks ago," Goh says. "We discussed the possibility of me doing a ballet for them for the '86-'87 season. In March I'll be leaving the country again.

"Where to? Can't I have any secrets?"