What has remained constant throughout James Blake’s career — from his basically instrumental, sample-heavy, early E.P.s, to the steady turn toward full-scale R&B documented by his two studio albums — is that he has always seemed to be an artist in the process of evolving. For this reason, I was surprised when I turned on “Modern Soul,” a song Blake debuted on BBC1 last week. A possible selection from his forthcoming studio album Radio Silence, the song would have seemed right at home on Blake’s more recent L.P., 2013’s Overgrown. Like so much of Overgrown, “Modern Soul” is piano based and melodic, but also features electronic instrumentation and distortion. All is set to the background by Blake’s soulful baritone, sounding great, but pretty much the same as ever.