Not everybody felt that way, of course. Though it debuted at No. 5 on the Billboard 200 (after No. 1 bows for 1987's "Hysteria" and 1992's "Adrenalize") and went gold, "Slang" was Def Leppard's slowest selling album in more than a decade, which Collen says was a source of great frustration.
"Y'know, I think we could've put out 'Sgt. Pepper's' or "Dark Side of the Moon' and I think it would have been the same because it was Def Leppard and we had gotten lumped in with all the crap metal bands of the 80s that were kind of pale versions of us," Collen explains. "Nirvana had come along and everything had changed. What was very interesting was people said they didn't like it so much because it didn't sound like us, but we set up in a villa in southern Spain and pretty much recorded live, so it was actually closer to the mark than the other albums where we didn't play live and did the usual studio thing of putting one thing on at a time and building it from there."
"Slang" marked the debut of new guitarist Vivian Campbell -- who replaced the late Steve Clarke and also wrote "Slang's" first single, "Work It Out" -- and was the first Def Leppard album made without producer Mutt Lange since 1980's "On Through the Night."
"Anyone who isn't a Def Leppard fan, you play it to them and they love it," Collen notes. "They go, 'Wow, this is really cool. Who is it?' 'It's us,' and they go, 'Whoaaaa. This is really cool.' But, yeah, no one really heard it. There's the faithful few who absolutely love it and think it's the best Def Leppard album of all time, but it's a minority."
Collen says Def Leppard may play a few extra songs from "Slang" when it tours North America during the summer, and he's also "hearing some talk" about another Las Vegas residency to follow up last year's Viva! Hysteria shows at the Hard Rock Hotel and Casino. Meanwhile, the group members recently assembled in Dublin, Ireland, for some preliminary work on Def Leppard's next album, the first of new material since 2008's "Songs From the Sparkle Lounge."
"We're just writing," Collen says. "We're all just together and figuring out what we're gonna do. We've got some great ideas. We're definitely going to get some new music out for next year."
There might be some "new" old music as well. Def Leppard is continuing to record fresh versions of some of its biggest hits for iTunes -- "Love Bites" is next on the docket -- and plans to continue until it comes to terms with the Universal Music Group over digital rights for the material.
"I know I really wanted that to happen, and I don't really care now, to be quite honest," Collen says. "It would be kind of cool if it was up on iTunes, but if it doesn't happen that's great; we'll just re-record them. There's no problem there. The new 'Pour Some Sugar on Me' we did is really successful on iTunes and it sounds great -- kinda like the original only louder and a bit more aggressive, so that's kinda cool."
The Def Leppard members are continuing to work on outside projects as well. Frontman Joe Elliott is planning another release with Down 'n' Outz, his Mott The Hoople covers group with the Quireboys, while Campbell, whose Hodgkin's lymphoma is in remission, is working with fellow former Dio bandmates as Last In Line. Collen, meanwhile, is hoping for a summer release for the first album by Delta Deep, an "extreme blues" group that also includes Stone Temple Pilots bassist Robert DeLeo, drummer Forrest Robinson (Toto, India.Arie, the Crusaders) and singer Debbi Blackwell-Cook, the godmother of Collen's wife Helen Simmons.
"It really reminds me of early (Led) Zeppelin, that kind of blues stuff," Collen says. "It's got this firepower I haven't heard for years. This smacks you in your face and assaults you. It's really dirty and nasty -- even lyrically it's the real deal. I'm just really pleased to be part of it."