It’s probably terribly difficult to do. Perhaps, even, impossible. But if it is desired that the listener listen without preconception then shouldn’t, at least to some degree, the composer, the songwriter - the maker - create without preconception, too?
To this end, I may set some goals of ideas that I want to execute and, yes, in so don’t be I am preconceiving my intentions, but not my actions. There is of course much greater risk with this method, creating without preconception; it seems almost by definition to invite instability and nebulousness, and be prone to disaster. But it is also, presumably, a chance to create work that is enthralling, exhilarating, wild, and natural?