Nashville's biggest indie rock ambassadors Kings of Leon spent their first two albums creating libedo-driven, Southern-inflected garage rock equal parts Skynard and Gang of Four. But 2007's "Because of the Times" found the Followill boys injecting astral atmospherics into their bar-brawl riffage.

On their latest "Only By The Night," they continue to expand a sound that orbits ever-further away from the underground and their Music City zip code.

The first evidence comes in the Sputnik blips and guitar squalls of "Closer" that's immediately followed by "Crawl," a Zeppelin-inspired mid-tempo number propelled by a ragged bass riff and Bohnam-sized percussion. You can also tell that the guys are possibly pushing their sound skyward to catch a few airwaves on the New Wave dance rocker "Sex on Fire" or what may be their most commercial ode to U2 "Use Somebody."

The band's sound continues to grow along with Caleb Followill's vocals, which are more melodic and better yet, discernable than ever. Many times, this clearness doesn't reveal a great deal of depth, as tracks with titles like "Sex on Fire" will surely indicate, but it's worth noting that Caleb has discovered the power of enunciation without sacrificing his trademark dusty howl.

Through the album's 11 tracks, the Kings essentially start in space but fall back to earth for the album's latter half, which produces a mixed bag of moments.

They present a confident sexual swagger conjuring up '70s era Stones on "I Want You" and ride a four-note melody and unexpected Caleb Followill sincerity on "Revelry." But the Kings end up looking more like jesters on the soft/loud groove of underaged lust track "17" and "Manhattan," with My Morning Jacket-esque reverb that steers the album into hookless, jam band territory.

"Only By The Night" is a bit unbalanced in its consistency while being the Kings of Leon's declaration of wanting something bigger. Bigger sound. Bigger audience. Bigger venues. But it doesn't find the balance that kept "Because of the Times" at home in the clouds and in the jukebox. Let's just hope as these guys venture further into space they don't forget how to find their way home.