While The Second Disc continues to champion physical media, we recognize that some labels have begun to issue digital-only releases that bring together rarities from the vault or spotlight long-out-of-print albums. From annual copyright extension releases to vault-clearing initiatives, we figured our readers would like to know about some of the treasures that have been released online and on streaming services. So, from time to time, we will shed some light on the best of these digital compilations and reissues. Here’s today’s installment! UPP, UPP (Epic, 1975) Standard-Resolution Download: Amazon U.S. Stream:…