Criterion are releasing a Blu-ray special edition of Quadrophenia on August 28th in the U.S. with a new 5.1 audio mix for the film and lots of other extras:

-New high-definition digital restoration of the uncut version, with the original 2.0 stereo soundtrack as well as an all-new 5.1 surround mix, supervised by the Who and presented in DTS-HD Master Audio on the Blu-ray edition
-New audio commentary featuring director Franc Roddam and director of photography Brian Tufano
-New interview with Bill Curbishley, the film’s coproducer and the Who’s comanager
-New interview with the Who’s sound engineer, Bob Pridden, discussing the new mix, featuring a restoration demonstration
-On-set and archival footage
-Behind-the-scenes photographs
-PLUS: A booklet featuring an essay by critic Nick James, a reprinted personal history by original mod Irish Jack, and Pete Townshend’s liner notes from the album

Available on Amazon and all the usual outlets.