If you want to really get the scope of what the Philadelphia sound was capable of, don’t just stick to the albums — and when you get to the singles, don’t just limit yourself to the 7-inches, because the finest qualities of the Philly groove most often manifested through deep immersion and deft remixing. Tom Moulton became one of disco’s great architects in part through his work with PIR’s cream of the crop, taking the components of already-great music and tailoring them for maximum dancefloor impact, so much so that it practically necessitated the invention of the 12-inch single to accommodate the extended-length reworks at high fidelity. This 2012 box set is rich with best-possible-version hits, deep cuts, and obscurities ranging from the O’Jays’ 1972 classic “Back Stabbers” to the Jones Girls’ 1982 curio “Nights Over Egypt,” each and every one of them glorious to the last.