The Cuarteto Casals, a Barcelona-based string quartet, presented an odd grab-bag program Thursday at the Library of Congress. After a first half of quartets by Haydn, Shostakovich and Turina, the group was joined by Peabody Institute faculty guitarist Manuel Barrueco in quintets by Roberto Sierra and Boccherini.

The concert was bookended by the two strongest performances: Haydn’s Op.33 No. 3 and Boccherini’s “Fandango” Quintet, G. 448. In these two works, the group had the better of its two violinists in the first chair (they reversed for the others), and everyone used baroque bows. Although I quickly tire of most period-instrument groups, the Cuarteto Casals’ hybrid sound charmed the ear (other than the bows, the instruments’ setup was modern). The ensemble captured the hushed beauty of the Haydn scherzo perfectly, added humorous ornaments in the trio and made the finale’s passagework sparkle. The adagio was rushed in places, but overall, this was a delight.

The Shostakovich Quartet No. 7, though, was less successful.

Although the manic fugue had plenty of energy, rhythms didn’t fit tightly together. Elsewhere, although intonation was precise — so important in Shostakovich, with his long drones — the musicians seemed to play some other, gentler piece. The grotesquerie and irony seemed to go right by them.

Joaquín Turina’s “La oración del torero” is by far the most frequently played Spanish string quartet after those of Arriaga, but it is an arrangement of a work for lutes (there’s also an orchestra version).

The Cuarteto Casals milked its languid harmonies, stretching the piece out almost into a dreamlike state. But tonal richness is not this group’s strong suit, and for all its indigenous feeling and authority with the music, the work felt wan.

The Sierra quintet, “Fantasia sobre la Musica Notturna delle Strade de Madrid di Luigi Boccherini,” was written for these artists and is being premiered on this U.S. tour. It is sort of an audio version of a rock video; lots of intercutting split screens, and a mash-up of unrelated images. The piece did not evoke the “harmonious atemporal soundworld” the composer’s note said it would; it was irritating.

All was forgiven in the closing Boccherini quintet, a mash-up of a much different sort. The playing was scintillating, and in the fandango, the artists had the whole house bopping to the rhythm.

Battey is a freelance writer.