Have you ever found yourself admiring a couple in a long-term relationship — watching and listening to the way they interact and how their anticipations and reactions seem both well-honed and paradoxically spontaneous?

I observed something similar while experiencing the Emerson String Quartet's final Twin Cities concert Sunday afternoon. This is an ensemble founded in 1976, and three of its members have been there from the beginning. Yes, the fourth, cellist Paul Watkins, joined only 10 years ago, but perhaps that was a welcome spark of revitalization, for the group seemed fully invested in whatever it played on Sunday.

While the nine-time-Grammy-winning group's current farewell tour includes stops at large venues like New York's Carnegie Hall and Chicago's Orchestra Hall, Twin Cities classical music lovers had the privilege of a concert in the intimate confines of the 315-seat St. Anthony Park United Church of Christ in St. Paul. It proved an ideal setting for exploring the nuances of this enduring marriage and becoming immersed in the deep interpretations this group brought to everything it chose to play.

In the case of this Schubert Club Music in the Park Series concert, the musical visions brought to life under the bows of these string players were those of Joseph Haydn, Dmitri Shostakovich and Antonin Dvorak. That kind of lineup might lead a lesser quartet to opt for light, dark and medium moods, respectively. But the Emersons made certain that the complexity of each work was fully articulated.

While there was plenty of ebullient bounce to Haydn's Quartet No. 29, the slow movement echoed with urgent sadness and a vulnerability that made me feel more in touch with Haydn's heart than I'd been in several years. Even during the high-energy finale, it seemed the group was decidedly eschewing any temptation to take this composer lightly.

That was especially welcome considering our next destination: Shostakovich's 12th String Quartet. While Haydn was largely making a living of creating musical entertainment for royalty, Shostakovich was the musical messenger for the age of anxiety that was much of the 20th century, struggling against threats and pressure from the Soviet government.

Written in 1968, his 12th Quartet was given a breathtakingly powerful performance, one at first menacing and mysterious before morphing into something like a musical panic attack, finally resolving in a place of mourning and trepidation. Its shifting moods showed the Emerson Quartet at the peak of its powers. It's unlikely I'll ever again hear Shostakovich's spirit channeled so eloquently. Midconcert standing ovations aren't that common, but this performance deservedly received one.

After that, Dvorak's 14th String Quartet could have sounded like an archaic museum piece, but this group didn't allow that to happen. The second movement's fiery folk dance bore plenty of heat, while the finale was a brisk and bouncy gallop at its best when what sounded like an impending eruption instead thinned to a whisper and headed off in a different direction.

But, as on the Haydn, it was the slow movement that left me most avidly admiring this foursome's artistry. The glances and subtle gestures made clear that they were still collaboratively crafting interpretations on the fly after all these years, their subtle smiles betraying their enjoyment. A brief Dvorak encore served as a warm farewell from a group that will remain a legendary musical partnership.

Rob Hubbard is a Twin Cities classical music writer. Reach him at wordhub@yahoo.com.