Sounds Like Uncharted Territory Worth Return Visit : Pop music review: Emmylou Harris joins Daniel Lanois and band mates in natural meeting of Quebec, Appalachia and the Delta.

If Emmylou Harris singing with Gram Parsons some 25 years ago made for a post-hippie George and Tammy, what does Harris singing with Daniel Lanois make?

A scintillating Sunday evening at the Coach House is the immediate answer.

Harris, who since Parsons’ death in 1973 has set the standard for country-music independence while exploring all corners of the country-folk-rock overlap, sat in for a handful of songs with the illustrious Quebecois musician-producer, best known for his atmospheric sonic sculptures with U2, Peter Gabriel, Bob Dylan and others.

The show would have been terrific even without Harris’ not-too-secret appearance, which was scheduled to be repeated at Lanois’ show Monday at the House of Blues.

For the bulk of the concert, done without the guest vocalist, Lanois and his supple band mates, jazz-based drummer Brian Blades and R&B; bassist Daryl Johnson, brought a vivid live dimension to songs from Lanois’ two stunning, though underappreciated, albums.

Lanois is a guitarist with a brittle, Hendrixian touch and a powerful writer with a penchant for tales of failure and redemption ( lots of water imagery). He draws on a wide spectrum of folk, rock and soul influences, from the Acadian playfulness of “Jolie Marie” to the U2-ish spirit of “The Maker” to the pounding fury of “Brother L.A.”

The choice of outside material was just as strong (and waterlogged), from Dylan’s “Hard Rain’s A-Gonna Fall” to William Bell’s remorseful “You Don’t Miss Your Water,” with the dynamic free-floating, near-telepathic interplay of the trio giving each number a soaring quality.

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But the surprisingly natural mixture of Harris’ familiar, belle-like lilt with Lanois’ array of unrefined guitar punctuations and soundscapes gave the middle of the show a lift. The teaming was more compelling live than on Harris’ new “Wrecking Ball” album, which, for all its pleasures, too often sounds like Lanois’ music with Harris’ distinct voice grafted on. In this teaser of a full tour expected in early 1996, the effort sounded like a true collaboration.

And it looked even more so, with Harris exhibiting joyous, heartfelt affection for Lanois, Johnson and Blade. Nowhere was this more evident than in an a cappella, Johnson-led gospel number with all four smiling faces pressed closely around two microphones.

It was a melting-pot moment--Harris’ Southern folkie roots dovetailing neatly with Lanois’ French Canadian foundations and Johnson’s and Blade’s Louisiana soul.

Most of the show emphasized the places where these musics meet, the common threads of immigrant cultures from Quebec to Appalachia to the Delta seeming to be the guide in the selection of material from Harris’ new album.

But even Jimi Hendrix’s gorgeous “May This Be Love” was a perfect fit--and you never would have thought of Harris and Parsons doing that song, let alone George and Tammy.