Ensemble 4.1, a chamber music group from Germany, boasts an unusual name, and its instrumentation is just as unusual: In a world filled with string quartets, Ensemble 4.1 features players on oboe, clarinet, bassoon, horn and piano.

The group bills itself as a piano windtet, and Ensemble 4.1 brings its unusual sound to the mid-valley for a Wednesday night concert. It's part of this year's Chamber Music Corvallis lineup of concerts.

Ensemble 4.1 began in 2013, when the five musicians in the group were recruited to play a series of concerts in Pakistan. In an interview with The E, pianist Thomas Hoppe noted that three of the five were familiar with each other, but the five men never had played all together until beginning the rehearsals for the Pakistan shows.

The chemistry between players is such an important part of a chamber music ensemble, and for Hoppe it was apparent from the start that the players in Ensemble 4.1 were a good fit.

It's a chemistry that continues when the players are offstage as well, he said: "If you go on tour together, you have to spend a lot of time with each other. You don't have to get married, but you have to have much friendship and respect."

Since those initial dates in Pakistan, Ensemble 4.1 has continued its globetrotting ways, performing in cities such as Berlin, Istanbul, New York, Toronto and Shanghai.

Although the group's unusual instrumentation makes it stand out, it offers some challenges as well. Among them: While the repertoire for string quartets seems almost limitless, music written for Ensemble 4.1's instrumentation is considerably rarer.

Fortunately, Hoppe said, the group's oboe player, Jorg Schneider, is an "avid treasure hunter," combing through libraries and catalogs to find works suitable for the ensemble. That's work that fits in with the ensemble's goal of discovering rarely played compositions from the Romantic and Modern periods. 

"Many of these pieces are very wonderful," Hoppe said — and they often are written by composers who aren't well-known even to knowledgeable concertgoers.

For example, Ensemble 4.1's concert in Corvallis features a quintet by the Dutch pianist Theodor Verhey and another work by Walter Gieseking, who is much better remembered today as a pianist.

Hoppe said the Verhey Quintet in E-flat Major is "very well-written … a beautiful piece." And he called the Gieseking Quintet in B-flat Major "most sophisticated and complex."

The concert also includes a work by Mozart, the Quintet in E-flat KV 452. Hoppe noted that Mozart himself thought this piece, the second movement in particular, contained some of his finest writing. Beethoven shared that assessment and, inspired by the work, wrote his own quintet for the same combination of instruments.

Ensemble 4.1 is working to add to its repertoire by commissioning new works — and Hoppe noted that one particular challenge is finding shorter works to fit into a program, because many of the existing pieces are relatively long.

But short or long, well-known or relatively obscure, Hoppe said that Ensemble 4.1 focuses on one goal while performing: "To provide a quality concert with quality music for this instrumentation."