Editing Dream Theater (section)

=== ''Octavarium'' (2005–2006) ===
[[File:Dream theater live in Parigi 2005.jpg|thumb|Dream Theater after a concert in Paris during the first European leg of their tour (2005). [[Mike Portnoy]], [[John Petrucci]], [[James LaBrie]], [[John Myung]] and [[Jordan Rudess]]|alt=The five members of Dream Theater standing together in front of a drum kit and some amplifiers on a stage.]]
After their ''Train of Thought'' promotional tour, Dream Theater entered [[the Hit Factory]] studios in NYC to record their eighth album. They would become the final group to use the famous studio, which closed on April 1, 2005.<ref>{{cite web|url=http://digitalprosound.digitalmedianet.com/articles/viewarticle.jsp?id=45690|last=Moldstad|first=Frank|publisher=Digital Pro Sound|title=New York's Hit Factory Gets a New Identity|archive-url=https://web.archive.org/web/20161220093309/http://digitalprosound.digitalmedianet.com/articles/viewarticle.jsp?id=45690|archive-date=December 20, 2016|url-status=dead|df=mdy-all}}</ref>

''[[Octavarium (album)|Octavarium]]'' was released on June 7, 2005, and took the band's sound in yet another new direction. Its eight songs included a continuation of Portnoy's "[[AA Suite|Twelve-step]]" saga ("The Root of All Evil", steps 6–7 in the 12-step plan), as well as the [[Octavarium (song)|title track]], a musically versatile 24-minute epic rivaling "A Change of Seasons". ''Octavarium'' received mixed reviews from fans and has been the subject of spirited debate. ''Octavarium'' was the last album under their seven-album deal with [[Elektra Records]], which had inherited the contract upon its absorption of [[EastWest Records]].

Dream Theater started the [[Octavarium Tour]] extensively throughout 2005 and 2006 to celebrate their 20th Anniversary as a band, including a headlining spot on [[Gigantour]] alongside [[Megadeth]] and put together by frontman [[Dave Mustaine]], also featuring [[Fear Factory]], [[Nevermore]] and [[Symphony X]]. During a show on August 2, 2005, in Dallas, the band paid tribute to [[Pantera]]'s late guitarist [[Dimebag Darrell]] by performing the song "[[Cemetery Gates (Pantera song)|Cemetery Gates]]" as an encore. In addition, was the unexpected appearance of fellow musicians [[Russell Allen]] (Symphony X vocalist), [[Burton C. Bell]] (Fear Factory vocalist) and [[Dave Mustaine]] (Megadeth vocalist/guitarist), who joined the band on stage to perform parts of the song.

Dream Theater later departed from Gigantour 2005 a few dates before it ended and continued on with their own series of concerts, several of which were recorded and released for the band's fanclubs. The 20th anniversary tour concluded with a show at [[Radio City Music Hall]] in New York City on April 1, 2006. Though the show had minimal promotion, it was sold out days after tickets were made available. This show, which was recorded for a CD/DVD called ''[[Score (Dream Theater album)|Score]]'' released on August 29, 2006, through [[Rhino Records]], featured songs from the band's entire history, as well a second half accompanied by a full symphony orchestra (the "Octavarium Orchestra"). This release was the band's third Live DVD release to be certified Platinum in the US on October 11, 2006.<ref name="riaa.com" />