Styx finally hit the multi-platinum jackpot with a trio of hit records in the late '70s, after spending the better part of a decade struggling to achieve their mainstream breakthrough. Then, emboldened by success, they went for broke with an ambitious gamble that paid off with their only No. 1 album to date.

To reach the top of the charts, Styx had to endure an arduous uphill climb filled with challenges both inside and outside the band's ranks. "We've always been different personalities," guitarist Tommy Shaw told Kerrang! in 1981. "I remember in the old days, when we couldn't afford to buy clothes, we would look like we didn't know whether we were going to be Jackson Browne or Kiss. ... We were all over the place. We couldn't agree, so nothing emerged as a common image for the band. We used to fight about it."

While they found their footing as a band, they foundered on the charts where consistent success eluded them until the release of 1977's The Grand Illusion. A triple-platinum hit, their seventh LP kicked off a string of bestselling albums and singles that continued with 1978's Pieces of Eight and 1979's Cornerstone. Along the way, as Shaw put it, "osmosis finally got the best of us," and they started to truly gel as a creative unit.

Still, there were cracks in the foundation. Shaw and fellow guitarist James "J.Y." Young favored a more basic, rougher-edged rock approach, but frontman Dennis DeYoung always had loftier ambitions for Styx. When his compositions started gaining the traction they'd worked so hard to achieve on the charts, Styx found it difficult to argue with his quest for a more complex, expansive sound that made room for sweeping ballads alongside their rockers.

As long as the records kept selling, it was easier to put those concerns on the back burner, so when DeYoung pushed for their 10th LP to be a concept album that used the gala opening and eventual abandonment of Chicago's Paradise Theatre as a backdrop for some pointed commentary on the state of America in the late '70s and early '80s, the group responded with one of its most accessible, well-rounded efforts. Titled Paradise Theatre, the record arrived Jan. 19, 1981, and immediately added another entry to Styx's growing stack of hits, cementing their status as one of the era's biggest bands.

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As with any concept album, the key to Paradise Theatre's mainstream success lay in the listener's ability to enjoy the songs without necessarily caring about — or even being aware of — the narrative arc that was supposed to hold them all together. Presented as a cohesive whole, the record was still easily parted out to pop radio, where Shaw's "Too Much Time on My Hands" and DeYoung's "The Best of Times" cracked the Top 10. The group's rock credibility was further maintained with a pair of AOR hits: "Rockin' the Paradise" – a co-write among DeYoung, Shaw and Young – and the Young/DeYoung number "Snowblind," which had the added benefit of being singled out by religious fundamentalists as "Satanic."

Paradise Theatre's triple-platinum sales and No. 1 chart status seemed to make believers out of DeYoung's bandmates, at least temporarily. Admitting that they'd been "skeptical" of the notion that the record-buying public would respond to the album's concept, Shaw even suggested that for their next release, they might follow their ambitions even further outside the mainstream.

"We got away with it, which is real rewarding," Shaw said. "All of us love the theater, like Broadway — I like all it encompasses. I love being taken in, being drawn into it and believing everything, and the technical aspect — being able to do so much with so little. We're trying to go further and further into that — not to hang ourselves by the neck; we'd still like to keep an audience — but I think we'd like to get even more daring and progressive and involve a little bit of a risk."

Shaw's prediction would prove prophetic, although the results weren't the unifying success Styx enjoyed with Paradise Theatre. When they returned in 1983 with their next effort, Kilroy Was Here, DeYoung's theatrical vision for the band provoked a split with Shaw, who quit prior to the release of the 1984 live collection Caught in the Act. For the remainder of the decade, the band slumbered through a lengthy hiatus.

Styx went through a number of lineup changes after finally reconvening, and following DeYoung's eventual ouster in 1999, they've mainly concentrated on live performance. Aside from arguably representing the creative apogee of this group's classic incarnation, Paradise Theatre also remains Styx's sole No. 1 album — and an evident source of lingering fond memories for DeYoung, who restaged its tour for a DVD release in 2013.

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