Numan isn't the only indicator that the balance of power between America and Britain in rock is teetering toward us Yanks again. While the Brits' exports of the moment seem to be cool, commercial synthesizer bands (Human League is another example), new American bands are busily synthesizing a broad range of styles to produce some of today's most visceral rock. As these two releases prove, San Francisco is reasserting itself as a creative cradle. Originally signed to 'he adventurous local label 415, and now co-released by Columbia, Romeo Void and Translator disdain flagellatory lead guitar breaks, relying on bracing, steely block chords and a dark, snappy rhythm section that makes nearly every cut insolently sexy and danceable. Romeo Void's vocalist and lyricist, Debora Iyall, has been aptly compared for sound and impact to the Pretenders' Chrissie Hynde. Both declaim as often as they sing. When Iyall suggests, in Never Say Never, "I might like you better/ If we slept together," it's as menacing as it is tempting. Benjamin Bossi's wailing saxophone adds exotic atmosphere. Warmth is at a premium in New Wave or "post-punk" (pick a label), and Translator integrates it without simpering. The quartet resurrects a bit of the ringing folky guitar textures of its San Francisco forebears, the Jefferson Airplane and the Byrds, as well as vocal harmonizing worthy of that great lost '60s group, Moby Grape. One unique treat in Translator's debut is hearing the band switch effortlessly from a nasty whip-cracker, Favorite Drug, to a tender, even pretty ballad, Everywhere. This is muscle music, but with a heart.