Max, I agree that Boxing Mirror is a spectacular record - a top ten all-time favorite in my book. However, I don't think that the sawing cello Escovedo uses there is what the OP was referring to. Similarly, the use of a string quartet is a different "different idea". Escovedo has covered an astonishing range of expression over the course of his career and his use of strings is IMO right at the top of the rock n roll heap. However, I think that his use of strings is a very different kettle of fish than The Moody Blues or The Zombies as cited in the OP.