Relevant Radio already has a station in the NYC market, 1430 based in Newark with 5000 watts 24/7. So I'm not surprised by them picking up 640 in the Philadelphia market, licensed to Mount Holly NJ (50 kw days/950 watts nights). Philadelphia already has Catholic EWTN affiliates in a number of suburban communities, 1420 Coatesville PA, 1570 Doylestown PA and 1260 Trenton NJ but 640 will not duplicate those stations' programs.
Relevant Radio is based in Milwaukee, Wisconsin, with most of its stations in the Midwest but is expanding to the East. The other, larger, provider of Catholic radio in the U.S. is EWTN, which started out in Alabama as a satellite and cable TV operation. There are some other providers, such as Immaculate Heart Radio on the West Coast, with a mix of their own shows and EWTN nights and weekends. Relevant Radio does all its own programming, live from 7am to 7pm weekdays E.T., repeated nights and weekends, with no carriage of EWTN.
I'd say Relevant Radio is a first-class operation, sounding like a conventional Talk Radio network. The hosts appear to be radio professionals who know how to move a show forward and are comfortable with radio formatics. EWTN is more doctrinal. There are one-hour shows hosted by priests and bishops and more formal prayers.
As AM station prices fall and fewer young people listen to AM, many AM stations will super-serve a select audience, be it religious or ethnic. Catholics are late in coming to radio vs. evangelical Christians, so Catholic organizations will likely do more buying.