Complete string quartets? Aren’t there just two? Not exactly. The Kreutzer Sonata and Intimate Letters quartets are both from Janácek’s last years, inspired by his intense romantic attachment to Kamila Stösslová, a much younger woman. For the latter work, the composer originally planned to employ the exotic viola d’amore instead of a modern viola. This instrument peaked in popularity in the seventeenth century—Bach wrote for it—and has six or seven bowed strings plus a number of strings beneath the fingerboard that resonate sympathetically. On this Audite SACD, the Mandelring Quartet plays both versions of Intimate Letters, with viola d’amore specialist Gunter Teuffel sitting in for the group’s usual violist. The substitution of Janácek’s “instrument of love” subtly transforms the work. As a solo voice, it’s gentler-sounding and more nuanced in expression; the ensemble’s timbral blend is softened, too. The Mandelring delivers idiomatic performances that capture the nervous, speech-like character of Janácek’s music as well as its melancholy-tinged lyricism. Audite’s aural perspective is front-row- immediate, with sharp dynamic contrasts and a widely spread soundstage.