Cellist Matt Haimovitz is known for expanding perceptions about his instrument. That includes a career-long championship of contemporary music, as well as performing in unexpected venues, such as his 2009 concert at Arlington’s Iota Club and Cafe. He did both in a weekend of performances for two of the city’s most artistically fecund museum concert series.

On Saturday, Haimovitz helped to reopen the free concert series at the Freer/Sackler, the twin museums that just underwent an 18-month renovation. In three mini-concerts, spaced at regular intervals throughout the afternoon, he combined one of Bach’s solo cello suites with a new “overture” by a living composer.

Over the past decade, the 46-year-old Haimovitz has matured as a performer, especially evident in the Bach suites. Haimovitz played the suites with an older baroque-style bow, and his articulations were varied and detached, reflecting an awareness of the historical performance movement. Heavy rubato occasionally obscured the dancelike nature of the music, especially in the slower pieces.

The idea of adding introductions to the Bach suites may seem superfluous, since the pieces already open with a prelude, but each of three overtures added an intriguing flavor. The repetition and arpeggiation of the G-major suite are often echoed in the music of Philip Glass, but his “Overture to Bach” was instead a sort of tragic aria, based in the relative key of E Minor.

Du Yun, who won the Pulitzer Prize for music this year, expanded on the mournful D-minor suite in “The Veronica,” evoking Orthodox chant amid a haze of delicate but dissonant effects. Vijay Iyer wrote the longest overture in “Run,” a piece that builds on the C-major harmonic series as an extension of Bach’s piece in that key, the “home key” of the cello’s tuning.

The Asian connections of these composers were part of the reasoning behind having Haimovitz perform in the Freer’s ­ultra-resonant,­ doorless Japanese screen gallery. On the other hand, no one would have had to go without a seat in the Freer’s auditorium, and the extraneous gallery noise would have been lessened. Wanting to listen exclusively to the music, after all, is not about sanctimony or exclusion, much as someone enjoying a fine meal would not want random spices thrown into it during tasting either.

On Sunday afternoon at the National Gallery of Art, Haimovitz joined forces with violinist Lina Bahn to provide the musical thread of a multimedia performance called “Voices of the Ocean.” The aquatic theme was centered on “Proteus,” Adam Borecki’s reimagining of a Vivaldi double concerto, whose three movements were spread throughout the program. In choreography by Lynn Neumann, dancers Aidan Feldman and Maya Orchin moved around the central fountain of the West Garden Court, in costumes made of rustling plastic bags.

Most of the performance was solely music, with the two amplified string instruments mixed with electronic sounds emerging from speakers around the space. Little of the charm of George Crumb’s “Vox Balaenae” survived in Jordan Nelson’s adaptation, “Vox Submersi,” and the most oceanic music was the sixth movement of Philip Glass’s “Partita No. 2” substituted by Haimovitz for the originally planned piece, the prelude from Bach’s Cello Suite in G.

Poems by Melissa Tuckey, read over and around musical accompaniment, were the clearest statement of the ecological meaning of the work, with explicit references to recent disasters caused by hurricanes, flooding and wildfires. The overall impression Haimovitz had created over these two days was of a performer seeking ways to challenge not only himself but listeners. Furthermore, he did so in a way that felt more reasoned and introspective than earlier in his career.