“Less is more” describes both the Moxie Strings and their new album, Breathe. Diana Ladio and Alison Lynn, on five-string violin and electric cello respectively, have long managed to make their nine-string duo sound like a much bigger ensemble.

They started performing as a duo a dozen years ago, playing primarily traditional Celtic music, and gradually broadened their repertoire with original tunes that brought in rock, roots, and Americana influences and showcased their considerable classical training and instrumental prowess. While Breathe, subtitled An Album of Slow Tunes, is comprised of pieces that utilize only the low end of the metronome, it still projects plenty of power and potent emotion.

As on their previous recordings, and in their live shows, there is no singing on Breathe, yet the wordless music of each piece conveys the title’s gentle advice and offers the means to follow it. Seven out of the eleven tunes are waltzes, and the music is peaceful, meditative, and coherent–yet never monotonous. Ladio and Lynn treat the familiar one-two-three rhythm, as well as the other rhythms of these sedate tunes, in creative ways, mining a considerable range of tonal colors from their instruments. Like a river or the sky, their sound palette is homogeneous yet ever changing.

The gorgeous “Go in Beauty” sings in a Celtic-inspired melodic and harmonic language, except for one startling, but fitting, bluesy note. “Wonderwall,” the 1995 Oasis hit and the only tune on Breathe not written by Ladio or Lynn, retains hints of its original rocking, propulsive drive, but without any of its pugnacious attitude. Some tunes employ additional instruments, guitar, piano, and electronic sounds and effects–but always used in minimalist ways, as surprising accents rather than lead instruments. On the aptly titled “Choose Joy,” which Lynn wrote for her first niece, she uses less than two dozen chiming piano notes. On the intentionally open-ended “Untitled” (Ladio says “Leaving it untitled was our way of allowing the song to serve everyone differently”), Ladio adds a handful of barely audible, yet effective, bass thumps, using a porch board, a foot-driven electronic percussion instrument.

Any musician will tell you that playing soft and slow is harder than playing loud and fast. You can’t hide inexpressive tone, shaky intonation, or unsteady rhythm on a stately tune, especially when there are few or no other supporting instruments. Ladio and Lynn’s playing on Breathe is unvaryingly precise and warmly communicative.

The Moxie Strings’ record release concert at the Ark on August 4 will no doubt feature the heartwarming tunes of Breathe, but having seen them rock the stage and the dance floor with the best of them, I’m certain they’ll mix in pieces that will also raise heart rates.