The techno-pop duo that makes flamboyant gay sensibilities palatable (and marketable) to the Luke Perry posse recently entered the U.K. singles chart at No. 1 with Abba-esque, a delicious EP of four '70s schlock-pop ABBA tunes which further proves how perverse the British sense of humor can be. Erasure reverently tarts up ''S.O.S.'' giving it a swirling electro edge and ''Take a Chance on Me,'' as keyboard whiz Vince Clarke pumps the '70s gems full of '92 club aggression. Camp aside, Erasure digs that ABBA were Euro pop gods, and they pay respect with a frothy testimonial that has its tongue in the right place.