* * * 1/2"SECRETS OF THE BEEHIVE." David Sylvian. Virgin. After almost a decade as one of the world's best and most pleasant Bryan Ferry imitators in both his solo career and his earlier service in the English group Japan, Sylvian comes closer than ever to establishing his own style here. He's a melancholy baby whose somberness still sometimes seems too affected, but like last year's beautiful double-LP "Gone to Earth," "Secrets" captivates the listener with its mellow, moody mood, smoky vocals and willowy instrumental background. The chief difference on "Secrets" is a further supplanting of the Ferry mannerisms with some that seem derived from the late, great Nick Drake. The result may not be technically original, but the blend is alluring and--perhaps paradoxically--unique, because who else is taking a similar approach these days? Only, and more and more occasionally, Ferry himself.