NASHVILLE:Imagine the rush of singing in front of thousands of fans, then turning around to find Keith Urban and Vince Gill in your band. That's the experience some of country music's top stars will have at the All For The Hall benefit concert Tuesday night.

Urban and Gill, as musical directors for the Country Music Hall of Fame and Museum fundraiser, have merged their bands and are sitting in all night. ''It would be awesome if we could keep it this way forever,'' Little Big Town's Karen Fairchild said after rehearsals Monday.  ''I don't think we could afford it,'' bandmate Kimberly Schlapman said. ''But it is amazing to be up front singing and turn around and there's Keith Urban and Vince Gill. I'm like, 'Yeah, I'm impressed with myself.''

Gill and the Australian star Urban come from band backgrounds and weren't about to pass up the chance to be part of the gang again.   ''I love playing,'' Gill said. ''I like being invited to play. I like it when people think enough of my playing to invite me to play. ... You never grow tired of that.''

The first two All For The Hall benefits raised about $1 million, and this year's installment sold out in a day.   The theme for the fundraiser is duos, vocal groups and bands, and the lineup includes Lady Antebellum, Rascal Flatts, Miranda Lambert's Pistol Annies, Alabama, Alison Krauss and Union Station, The Band Perry and Thompson Square.

Urban promised a couple of surprise guests. ''Both titans, definitely,'' Urban said.  This will be one of his fans' first chances to see Urban perform since surgery late last year to remove a polyp and a nodule from his vocal cords.

In a phone interview last week, Urban said he was worried he might lose some of his singing ability. But he actually emerged with benefits he never imagined.

''I think if a footballer in their 40s was given their knees back like they were in their early 20s, that's kind of how I feel right now,'' Urban said. ''It's an extraordinary feeling of freedom.''He has been working with a vocal coach to strengthen his voice.

''I already feel that this next album, the thrust and the pull as a songwriter, is to talk more about some of my stories, personal stories, beyond my relationship with my wife (actress Nicole Kidman) and subjects that I've never really tapped into that much,'' Urban said. ''So I think getting my voice back has sort of been a metaphor for finding my voice more so as well as an artist, broadening it, really, to the things that I want to write about and I feel ready to write about that I guess I haven't in recent years.''