Singers appear most often as either star soloists displaying unique voices or amidst a capacious choir celebrating the power and glory of the human voice. For sheer musical delight, however, it is difficult to match a vocal chamber ensemble in which individual voices and the group's blend remain in perfect, precarious balance.

Tomorrow, the Honolulu Chamber Music Series will showcase Chanticleer, a choral ensemble of 12 singers, ranging from sopranos to basses — all male.

Yes, there are adult male sopranos, and no, they are not just singing falsetto.

Fifty years ago, there were very few male sopranos, and most of those were falsettists. In recent decades, high male voices have experienced something of a renaissance, and falsetto is now only one technique of many.

Perhaps not surprisingly, the renaissance has also given rise to considerable controversy. As recently as the 1980s, eminent music dictionaries stated unequivocally that there were only three male voices: bass, baritone and tenor. Period.

Are these high male voices developed falsettos or full voices? Do we call them countertenors? Altos? Mezzos? Sopranos? Or still falsettists? Definitive answers are still sorting themselves out, but the singers aren't waiting around for answers.

In Chanticleer, the all-male timbre creates a homogenous, tempered-chocolate quality, while the range of voices allows for a full tonal spectrum. Small enough for every voice and every line to be heard distinctly, the ensemble is still large enough for full close harmony.

Tomorrow's program ranges as widely as the voices, from medieval plainsong to the 20th century, sacred to secular, and classical to folk song.

One set of songs is drawn from the works of Carlo Gesualdo (c. 1561-1613), a quirky composer who lived an even quirkier life. First a count, then prince, he committed double murder (he caught his wife with another man), lived a life of political intrigue, morbidity and depression, and eventually died estranged from his second wife and in social isolation, shortly after the death of his last child.

Gesualdo's one refuge was his music, an unconventional music full of gnarly harmonies and counterpoint proceeding according to its own set of rules. Some of his madrigals achieve an almost otherworldly quality.

At the other end of the spectrum, the program's final set presents selections of folk songs from the British Isles and Pacific, including an arrangement of Queen Lili'uokalani's "Aloha 'Oe."

In between, Chanticleer will perform Palestrina, Messiaen, Poulenc, Tavener, Brahms and more.

Now in its 29th year, Chanticleer has earned a reputation for choral excellence, a reputation disseminated through recordings and recognized by an array of awards but built on live performances.

Chanticleer's is a sound that is better heard than described and best heard live to be fully appreciated.