FIRST OFF . . .

The $6 million British musical “Chess” may be checkmated this Saturday, when the show’s producers have said they will close the show if mediocre box office at the Imperial Theater in New York doesn’t improve. But the show’s probable demise will not affect the scheduled release of the original, Broadway-cast soundtrack album, still on for July. An RCA Victor spokesman said late Tuesday that the decision has been made to go right ahead with the release--whether the show goes on or no. “Chess” has been playing to about an 80% capacity crowd since its April 28 opening, but 50% of those were half-priced seats (last week, the show took in $341, 522). Three years ago, a soundtrack album of the original British cast did moderately well and spawned a Top Five pop hit with Murray Head’s single of “One Night in Bangkok.”