If Marcel Duchamp had ever composed an opera, it would probably have been something like Vincent McDermott's one-act "A Perpetual Dream," which is currently showing at the Round House. Beautifully sung by Marilyn Boyd DeReggi, with a text that sometimes resembles Samuel Beckett, and a highly surreal sequence of stage movements and images, it includes two players from the Round House company, Gayle Behrman and Mark Jaster. They straddle the imaginary borderline between mime and dance in their stage movements, and at one point they take seats in the audience to make rather negative remarks about what is happening on the stage.

The opera is a collage of dreams that begins in anguish and anxiety, modulates through a spectacular mad scene, includes a nocturne played with one finger on a toy piano, and ends on a note of rather undefined hope.

It comes as the climax of a show, called "Spectrum" and playing through Sunday evening, that ranges from horror to manic laughter. Other highlights include an interpretation of Lewis Carroll's "Jabberwocky" and a drama called "Accident," in which the hero receives a job promotion, is run over by a taxi, undergoes a hilariously macabre operation, dies, is rejected from heaven, is reincarnated and tries to crawl back into the womb, all in about 10 minutes.

My mime hunger, killed by too many imitations of Marcel Marceau, was revived by five mimes from the Round House company who gave a special flavor even to such simple items as a man and woman on a roller coaster. Particularly memorable was a sequence of blackouts in mannequin poses, a number called "Relationships," in which people were portrayed as wind-up dolls, and a hilarious set of orchestral musician imitations called "Violin Fantasy," with music by Vivaldi, Bach and Tchaikovsky. Much of this material and other items on the program are the work of Michael Littman, who, on the evidence of this show, may be a mad genius.