Some concerts are so palate-cleansing I need to live in their dazed glow for a while, and Diamanda Galas‘s show at the MCA on Thursday (the first of two last weekend, both sold out) is definitely one of them. I’ve been a fan of hers for years, yet never managed to catch her live before. She’s always had a way of playing a city just weeks before I moved there or weeks after I moved away, and she hasn’t been seen in Chicago for more than a decade. Her circulating repertoires of “Songs of Exile” (the program I saw) and “Guilty, Guilty, Guilty” (the one on Saturday) don’t have the overwhelming operatic cohesion of her AIDS-related “Masque of the Red Death” albums and performances of the late 80s and early 90s, or of 2004’s Asia Minor genocide requiem Defixiones: Will and Testament. At the MCA she played up her dark cabaret diva side as the equal of her avenging-demon, professional-mourner side, and the two facets strike an uneasy balance. But it’s like Halloween is the cute party holiday and Samhain is the night when the spirits of the dead return. You see the difference? It’s like night and . . . night.

On Thursday Galas got started nearly half an hour late, like the diva she is, and I don’t think anyone really begrudged it. Not when her version of the legendary suicide song “Gloomy Sunday” (now there’s a party track for you) unscrewed the top of our skulls and filled it with a scent of bitter almonds. She closed “25 Minutes to Go” with a slam of cold darkness like a coffin lid (the smoky lights having already cast dimly colored veils around her reportedly stage-fright-afflicted self) and she turned “O Death” into a form-changing keen meant to set all the dogs to howling the next holler over, because they hear the banshees first. The one that got me, though, was her “Keigome Keigome” (I’m burning, I’m burning), a rembetiko song by Nikos Gatsos and Stavros Xarhakos. (There’s a YouTube video of her performing this song in London, though the stage is even darker than she usually likes it, the sound quality is terrible, and it cuts off before the best part. But you can get an idea.) It haunts me. I heard it in my sleep. I heard it when I woke up. It was all about the tomblike echoing spaces in her piano and the way she lets that voice growl and roar before erupting into shrieking high-end ululations that sound like a flock of carnivorous birds beating themselves to death against a vaulted ceiling. To call it beautiful is like calling a mushroom cloud beautiful. I mean, of course it is, but to say so is kind of trivializing.

What I want to know, though, is who was Mr. Fuckyouman up in the back row early on? What was his deal? Please, if you can, dish here.