For the first decade or so of its existence, the CMJ Music Marathon — an outgrowth of the then-grassroots tipsheet College Music Journal — was an invaluable resource for A&R folk and diehard fans looking to get an early glimpse of the next big things and see already big things in surprisingly intimate contexts.The 29th edition of the confab — the first to be held since its parent merged with John Scher’s Metropolitan Entertainment — was held last weekend in New York. While it didn’t have much of the urgent buzz that surrounded the proceedings in the go-go days of the mid-’90s, a slight uptick in attendance, estimated at 2% from 2008, and an influx of approximately 1,300 acts created an undeniably lively atmosphere at the 40-odd venues the event took over for five days. There was nothing terribly lively about the oddly named xx, one of this year’s more anticipated arrivals, but that was the idea. Positioned as something of a guitar-toting Kraftwerk, the Brits won friends and influenced people with an Apple Store performance that was lo-fi, high-drone and agreeably po-faced. At the other end of the energy spectrum was the highly touted Los Angeles-based Fool’s Gold, which incorporated elements of African high-life music that recalled “Graceland”-era Paul Simon, sans the intellectualizing. Uninhabitable Mansions — a demi-supergroup populated by members of New York’s Au Revoir Simone, Clap Your Hands Say Yeah and Dirty on Purpose — proved to be one of the fest’s surprise hits, thanks to a Brooklyn showcase at which they displayed plenty of minimalist charm. That band had a retro charm redolent of the so-called “love rock” movement born in mid-’90s Olympia, Wash., while the era’s angrier riot grrl flip side was chillingly channeled by New Jersey’s Screaming Females, led by the rivetingly livid Marissa Paternoster. As has been the case in recent times, the daytime portion of CMJ’s program — panels like the cheekily titled, artist-centric “But How Do I Get Paid?” — seemed oddly segregated from the evening performances. Still, there was enough life in the latter to make the prospect of a 30th anniversary blowout in 2010 seem inviting.