The newest Philly music festival? It's Hall & Oates' HoagieNation

The 1972 lyric about not wanting to spend another "fall in Philadelphia," Oates says, "wasn't about going somewhere physically, although we did go to New York. We needed to go somewhere psychically. We needed to expand our horizons and our dreams."

In the last decade, they have welcomed a millennial audience, as young bands like the Gym Class Heroes and Chromeo have embraced them. Stylish British band the xx sampled the 1981 H&O hit "I Can't Go for That (No Can Do)"  on this year's slinky hit "On Hold."

Hall sees the breakthrough as a result of his collaborations on his web show, with acts like the late Sharon Jones. "I think people finally understand what I'm really about, and what my motivations musically are. And I think it's changed people's perception, obviously to the good."

Oates concurs. He adds: "The digital revolution played into our hands without us knowing it.  All of a sudden, this new generation had the whole history of music at their fingertips. They can like what they like, and share what they like. And our songs have stood the test of time. We've been a very fortunate beneficiary of this broadening and opening up of a musical mind-set of a new generation."     

And when new fans want to connect with the duo, they've been able to find them,  on the road or, in this case, at their own festival. "That's the thing," says Oates. "We've never stopped working. We've always been that way, and we've never changed. We're a working band."