Near the outset of Keegan Theater’s spare but sprightly mounting of Krapp’s Last Tape, director David Bryan Jackson and actor Brian Hemmingsen allow themselves a little non-textual joke that feels at once Beckettian and pointedly post-Beckettian. The script calls for Krapp to rummage in a desk drawer, pull out a reel of tape, stare blankly at it, and put it back. Hemmingsen’s Krapp does that, then reaches back in the drawer and pulls out a cassette player at which he stares equally blankly. This obsolescence joke—existential at its core—could not have occurred to Samuel Beckett when he wrote the play in 1958, there being no cassette players then, but it’s an amusing accretion in an opus about a man revisiting a past self he doesn’t quite recognize. After busying himself with vaudeville tropes—seldom has a clown so enjoyed the “sound” of a banana, or slipped so deliberately on its peel—Krapp will mark this day, his 69th birthday, by listening to bits of a taped journal he’s been keeping for years. He’s chosen Tape Five in Box Three, the journal entry from his 39th birthday, and after much rummaging offstage for a tape machine, an extension cord, and a surreptitious drink or three, he will somewhat dejectedly hear that the voice on the tape is unmistakably his, though younger and brasher. Listening to himself describe the three bananas he’s eaten in celebration of his 39th birthday, and the gastric distress that inevitably followed, Krapp seems at once envious and dismayed. And as he listens to his younger self speak of a woman he’s bedded, a parent he’s lost, a ball he’s thrown ad nauseum to a dog, resignation consumes him. His life hasn’t been entirely joyless—“I suppose it’s better than a kick in the crotch,” he reasons—but it’s clearly not been all he’d hoped. Listening to his 39-year-old self sneer on the tape at his 20-something self, the 69-year-old sneers too. But the memories are fading, and with them, so is Krapp. The tapes sustain him, at least for now, and Hemmingsen makes the taping itself pretty antic. In fact, considering that the play is all about stripping away and reducing to essences, he is having one helluva giddy, flashy, high old minimalist time. But the result will be, as the title has it, Krapp’s last tape, and whether that means “final,” or merely “the most recent,” Hemmingsen’s stare as the tape rolls on and light fades away is unutterably sad.