It was somewhere around the discovery of adjacent vinyls by KC and the Sunshine Band and Boris Karloff performing a dramatic reading of “Peter and the Wolf” that it became clear: Not a mite of musical minutia would be left unattended to at WMUA’s vinyl blowout on Saturday. It was pretty overwhelming. There seemed a bin for every conceivable sub-generic categorization, not to mention the countless bins labeled “Weird” or “?!?!?!?” or “Who knows?”