The Guarneri String Quartet is preparing to call it quits after more than four decades as one of the world's premier chamber ensembles. With only one personnel change in all those years, violinists Arnold Steinhardt and John Dalley, violist Michael Tree and the relative newcomer, cellist Peter Wiley, have begun a farewell tour. The group stops in Denver tonight for a sold-out Friends of Chamber Music concert at the Newman Center. The Rocky's Marc Shulgold spoke with first violinist Steinhardt before the announcement of Dalley's cancer.

How did you all decide to retire?

We've been together now for 45 years - when would there be a better time? After 40 years? 50? 100? We just decided (to retire) at the end of last season. It's always been "one more year" with us. After we announced and people started asking, "But why do you have to quit?" I thought, "Ah - we picked a good moment."

How did the group come together?

Michael, John and I knew each other at Curtis (Institute of Music), but back then, we all wanted to be soloists. We did play chamber music, just for fun. When we graduated we went our separate ways. I was an assistant concertmaster with the Cleveland Orchestra in the early '60s. In 1963, we got together at (the Marlboro Music Festival) and decided to give it a go.

Until cellist David Soyer's retirement in 2000, the quartet remained unchanged. What impact did his departure and Peter Wiley's arrival have on the group?

Understand that David is 14 years older than I am. When we started, John, Michael and I were in our 20s, so he seemed ancient to us. But his experience was so valuable at the start - he knew what to do. David is 85 now and playing fantastically. He'll join us for the Schubert (C-major) Quintet in New York and Philadelphia. He was with us for 37 years, so when he decided to leave, we thought it was time for all of us to retire. But we loved what we were doing. Peter was the only one we thought of - we'd known him since he was 11. We decided that if he said "no," we'd retire. Of course, we didn't tell him that. He's such a loving individual and such a wonderful musician. Immediately, he shared his ideas with us. I think he moved the Quartet a couple of degrees off to one side.

There's a low-key approach to this farewell tour. Was that the plan?

We really haven't treated this season any differently. We always tried to include something off the beaten path. We'll play the Kodaly (Quartet No. 2) in Denver, a piece that most string quartet players don't know. With repertory, we've never had an interest toward cutting-edge stuff. Instead, we've chosen to look in dusty corners for pieces such as the Kodaly. We've had new works written for us, by composers such as Bill Bolcom, Lukas Foss and Ned Rorem.

What's next for the group?

We'll all remain active as professors in residence at the University of Maryland, passing on what we know. I'll be doing solo engagements, and Peter and I will be performing together in 2010. Plus, I'll be writing. I have some ideas for a possible book. I'm sure we'll remain friends. It's always been that way - we had wonderful fun at rehearsals, joking and sharing stories. We've always been very independent. It's not true that we couldn't stand each other. We've been incredibly lucky with our career, but we had to draw the line and call it quits. The timing on our farewell is just sublime.

Health update

John Dalley, the Guarneri String Quartet's second violinist, was recently diagnosed with prostate cancer. "John is on hormone treatment and will undergo chemo in mid-January," said manager Mary Lynn Fixler.

Until then the quartet's farewell concert schedule will not be affected. Originally, the group's final concert was set for May 31. Instead, eight programs in February have been rescheduled for October and November.

"They have every expectation of continuing to play again in March," Fixler said, adding that doctors are "very optimistic" about Dalley's recovery.

Guarneri String Quartet

* When and where: 7:30 p.m. today, Gates Concert Hall, 2344 E. Iliff Ave. (sold out)

* Information: 303-388-9839