Was the version of Suzanne Vega‘s “Tom’s Diner” that became a hit in 1990 the first mash-up? When two British DJs working under the name DNA pirated Vega’s a cappella performance (the original opened her breakthrough album, 1987’s Solitude Standing) and tied it to a Soul II Soul beat, the song — and Vega’s career — was born again. A wispy interior monologue became a club hit, Vega’s label took the enlightened step of buying the new recording rather than litigating it out of existence, and the singer spent her next two albums exploring sensual rhythms. The remix is included on Vega’s worthy 2003 best-of, which she’s still supporting with tour dates before returning to the studio this fall for her first album since 2001. (She has also made a private-issue live CD — how very DNA — available at shows.) In another kind of mash-up, Vega is co-headlining with Marc Cohn — winner of the cursed Best New Artist Grammy in 1991 and writer of the milquetoast classic “Walking in Memphis” — who, like Vega, peaked commercially before recording his best work.