U2 has hit the studio in Dublin to continue work on its next studio album with longtime collaborators Brian Eno and Daniel Lanois. "We're going to try and break new sonic ground and deliver a masterpiece," Lanois tells Billboard.com. "The sleeves are rolled up. Bono is all charged up with a lyrical angle."

As previously reported, U2, Eno and Lanois have spent time working on new material on three prior occasions in France and Morocco, and Lanois confirms the results are prolific.

"There's so much material," he says, referring to speculation that the sessions could yield two new albums. "When you get Eno and I and those guys in the room, before lunch there's like eight things."

"We've had some exciting beginnings via jam sessions," he continues. "Now we will pick our favorite beginnings and say, 'OK, that's a lovely springboard. Now what are we trying to say?' The springboards are sometimes melodic, sometimes riff-based, but I can assure you they are exciting."

There's no date yet for the project, which will be the follow-up to 2004's "How To Dismantle An Atomic Bomb."

CM8ShowAd("Middle"); In other U2 news, the group has contributed to a new charity single, "The Ballad of Ronnie Drew," proceeds from which will benefit the cancer-stricken Irish artist of the same name. The track will be available in Ireland only as a download beginning Friday (Feb. 22) and week later on CD.

In addition to U2, "The Ballad of Ronnie Drew" features appearances by the Pogues' Shane MacGowan, the Frames' Glen Hansard, Sinead O'Connor, Andrea Corr, Damien Dempsey, Ronan Keating, Chris de Burgh, Gavin Friday and members of the Dubliners.