The 2005 double-disc set Rock of Ages: The Definitive Collection is the second Def Leppard compilation to be released in the U.S. The first, Vault: Def Leppard Greatest Hits, appeared ten years earlier, and while the band was active in the decade separating the two albums, charting fairly consistently, it didn't have any major hits during that time, so the chief appeal of Rock of Ages versus Vault is that it covers more ground. Vault had 15 songs. Rock of Ages has 35, including all of the songs on Vault. Actually, the first disc of Rock of Ages functions as an expanded version of that earlier comp, adding two cuts. The second disc skips around their career, wisely concentrating on their early-'80s albums, which were somewhat under-represented on Vault, and adding a new song for good measure (a cover of Badfinger's "No Matter What," which is from their "forthcoming covers album"). While this may be too much Def Leppard for some casual fans -- for those listeners, the 2004 import-only collection Best of Def Leppard is a good choice, since it expands on Vault -- it nevertheless is the best overview of the group's career yet assembled, since it has not only the hits, but the sleek, glammy pop-metal that earned them the reputation as one of the biggest and best bands of the '80s.