Who’s Next might be the only Who tribute band in the world to have had the late John Entwistle pop in for a set. Then again, the great bassist known as “Thunderfingers” might have just been confused. After all, Who’s Next is so authentic, sporting exact replicas of the Who’s guitars, drums, amps and clothing, Entwistle probably thought he was playing in his own band. For, not only does the tribute act capture the pure power and energy of the Who, the musicians even look like Roger, Pete, John and Keith. Rock out to their expert renditions of hits like “Who Are You?,” “Pinball Wizard” and “My Generation” when the band makes a rare New England appearance at the Regent Theatre.