Donnacha Dennehy's new CD is absolutely a revelation. Courtesy of Contemporary Music Center of Ireland.

The "trickster," composer John Adams once called it — the persona he evinces in pieces like his Chamber Symphony, which he described as a cross between Arnold Schoenberg and Wile E. Coyote. He's (understandably) tried to distance himself since from the notion that his pieces collectively fall into one of two categories, either jest or earnest, but still it's clear, once in a while, when he's up to his old tricks again.

Case in point: One might reasonably suspect that Adams has revisited the aesthetic of the Chamber Symphony with the titular piece on his new CD, Son of Chamber Symphony (Nonesuch Records). The original was one of a kind in Adams' oeuvre, suggesting a close study of such great American weirdos as Frank Zappa and Mexico-based player-piano fiend Conlon Nancarrow. The sequel (self-deprecating title notwithstanding) defies the Hollywood law of diminishing artistic returns while still offering all of Chamber Symphony's daffy pleasures.

The other half of the disc, the even more bluntly titled (or untitled) String Quartet, might not be in deadly earnest — it's too vivacious for that — but neither is it as jokey as Adams' other entry in the genre, the winning John's Book of Alleged Dances for quartet and tape. As the (un)title suggests, this quartet is a serious entry into the august genre, and as such it is impeccably written — how is so much going on between only four musicians? As with the Chamber Symphony, impeccably performed by crack new-music ensemble ICE, the St. Lawrence String Quartet gives the John Adams String Quartet a first recording that seems likely to remain the benchmark.

None of this will be news to new-music nerds for whom John Adams has been a household name since he wrote Nixon in China. Composer Donnacha Dennehy is not — yet.

Grá agus Bás, Dennehy's CD for Nonesuch, seems likely to change that. The title piece brings a David Lang-style intensity to the accompaniment of Iarla O'Lionáird's traditional Irish sean-nós singing, but with textures that blur the line between timbre and harmony. Dennehy's Dublin-based Crash Ensemble, conducted by hardest-working-man-in-new-music Alan Pierson, performs with requisite energy and precision, although I did find myself wishing the electric distorted guitar could have been let off its leash just a little and allowed, just barely, to drown out the other instruments once in a while.

Dawn Upshaw has claimed that her musical partnership with Argentinian composer Osvaldo Golijov has made her a better singer; her recording, on Grá agus Bás, of Dennehy's Yeats settings, That the Night Come, suggest that she may be right. The piece itself is exquisite, framing Upshaw's voice with spectral whisps of color, and Upshaw's performance reveals a singer willing to take real risks. Both these discs are must-hears — but Dennehy's is absolutely a revelation.