All of a sudden, there it was.

A little more than an hour into his sold out show at Vancouver's Queen Elizabeth Theatre Sunday night, Robert Plant turned his back on the crowd, crouched down just a little and set his voice free.

He'd been keeping a tight reign on it all night, working carefully on country blues and gospel harmonies with the preternaturally talented Band of Joy.

No surprise, The Voice arrived during a smoldering rendition of Led Zeppelin's 1969 Ramble On, and magic did indeed fill the air. The playful smirk on the 62 year-old's grizzled face when he turned around revealed he knows a thing or two about his audience.

You see, Robert Plant has spent far more of his life on solo projects than he did fronting the band that's inspired pretty much every hard rock act in music history, but it's only lately that he's really begun to celebrate his early days.

Make no mistake. Plant is all about exploring new musical frontiers. But last night's combination of old and new is clearly what his fans have been craving. The singer, known for sweeping lyrics and a uniquely powerful voice, spent decades trying to escape the blast radius Zeppelin left behind when it crashed and burned in 1980. His work in the early post-Zeppelin years was inconsistent, his concerts almost devoid of references to the music that made him famous.

But something changed a few years ago, and now Robert Plant is in a comfort zone and on a roll.

His 2009 collaboration with bluegrass songstress Alison Krauss netted him an Album of the Year Grammy and his latest disc, titled "Band of Joy," is also getting plenty of critical acclaim. Now, Robert Plant seems more than happy to rekindle lifelong relationships with fans who want to thank him for providing the soundtrack to an infinite number of road trips, house parties and first kisses.

Plant's voice has changed considerably since his youth. He can't always reach the high notes, but he doesn't really need to. His voice is richer now and he's surrounded himself with other gifted vocalists.

The most powerful example of his penchant for collaboration last night was when he shared the microphone with Grammy winning singer Patty Griffin for a cover of the classic, "House of Cards." Plant introduced her as "the best singer in the band" and hard core fans may have been reminded of his haunting 1971 duet with folk songstress Sandy Denny on Led Zeppelin's "The Battle of Evermore."

From Denny to Krauss to Griffin, it seems Plant is well aware he sounds damn good with a woman. He also sounds damn good alongside a virtuoso guitar player.

If Jimmy Page was the perfect compliment to the early Plant's explosive voice, Band of Joy guitarist and co-producer Buddy Miller's more subtle, haunting sounds fit Plant's modern incarnation like a glove. Plant called Miller "the Captain of our ship" as together they took the Queen E on a moonshine soaked journey into the heart of American roots music.

When it was over, it seemed every face in the crowd was smiling and so was Robert Plant. He'd introduced his aging fans and their teenaged children to a relatively obscure but rich musical genre and they'd responded by standing on their feet and dancing for two hours straight.

He'd also let out The Voice for a few classics and safely put it back again -- the best of both worlds from a restless soul who seems to have finally learned how to explore new musical frontiers without turning his back on his legacy.