The new-music series at the Atlas Performing Arts Center may not be unique in the country, but it’s got to be pretty close: I don’t know of another series entirely devoted to presenting top-flight contemporary groups. Whether or not all of it is to your taste, if you want a snapshot of what’s happening among younger musicians these days, the Atlas series is a good place to get it.

On Friday night, the center offered the strongest evidence yet that there’s new vitality to Washington’s contemporary music scene. At 8 p.m., the Atlas presented the New York-based quartet So Percussion in an exhilarating John Cage tribute in its Lang Theater. At 9:30, the Library of Congress rented out the Sprenger theater for its own “Library Late” show, a double bill of the New York ensembles ACME and yMusic. The result was a contemporary triple-header that neither presenter had actually intended, but that certainly acted as a magnet for new-music audiences. Both concerts were reportedly sold out.

As if to alleviate anxiety that the first concert would run over and delay the start of the second, the So Percussion event was dominated by an electronic stopwatch projecting a second-by-second 90-minute countdown in glowing white numbers on the back wall. This set up an intriguing counterpoint, since the percussion pieces did not always mark time at the same rate as the stopwatch; there were interference patterns between what was heard and what was seen even as the presence of the stopwatch bound all the disparate works into a single block of time. (There was no intermission.)

So’s concert, called “We Are All Going in Different Directions,” picked up on the energy and quality of the Cage festival that opened Washington’s concert season — and featured some of the same pieces, including “Imaginary Landscape #1,” “Quartet for Percussion,” and “Inlets.” You’re not going to hear them done better; this group plays with an irresistible vitality. They juxtaposed some of Cage’s earlier percussion works — the concert opened with “Credo in US” from 1942, with swatches of radio samples and swoops on the prepared piano — with contemporary pieces like “Use” by the 30-something composer Cenk Ergün, who sat on stage with the violist Beth Meyers in silence until his piece activated both of them, he on electronics and she issuing little thoughtful lines from different points on the stage. So’s players — Eric Beach, Josh Quillen, Adam Sliwinski and Jason Treuting — also contributed some pieces of their own.

As the 90 minutes ticked down, the event crescendoed into a wonderful, anarchic collage of four different Cage works, dubbed “18’12”,” which included the assortment of Cage’s writings the composer collated as “45’ for a speaker,” read by a man dressed in Cage fashion in a 1960s slim tie and dark-rimmed glasses. Already we had several different measurements of time going on.

Meanwhile, the 36-minute mark was the cue to start Dan Deacon’s “Take a Deep Breath.” The piece (printed in the program) specified 14 actions that the audience was to perform at certain dictated points, starting relatively simply with vocalized exhalations, and growing more and more involved: One instruction was to put your phone on speakerphone, call someone not in the room, and ask them to sing. The audience was remarkably, unself-consciously compliant, though there was plenty of laughter as people tried to reassure absent family members of their sanity and sobriety (“Just as long as you’re not driving,” said one man’s mother as she signed off). By the time everyone had switched seats, multiple times (the final instruction), like a dance, there was an air of ease and camaraderie in the room that notably affected the listening climate; we were all in this together, having fun.

This was a concert rare in its delightful excellence, and consequently a hard act to follow, and neither ACME nor yMusic could quite manage to do it. These groups are part of the generation after So Percussion, young New Yorkers who merge in various combinations — three of the performers were in both ensembles, including the violist Nadia Sirota, a somewhat ubiquitous figure on New York’s contemporary scene these days. They’re ambitious and full of ideas, but — particularly after the crackling precision of So Percussion — they seemed a little callow, and their presentation fell back on the dutiful “Here’s a piece by X, and now here’s a piece by Y.”

ACME (the American Contemporary Music Ensemble) was represented by five performers and some not-very-strong music; the pieces might have benefited from better playing, and the players might have risen to the occasion with better pieces, but the combination was unsuccessful. Caleb Burhans, a talented composer who’s proficient on several instruments, was not quite proficient enough on violin to animate either Don Byron’s “Spin” (played with Timothy Andres) or John Cage’s String Quartet in Four Parts — a slow and spare piece that can be quite beautiful but that here seemed dreary. The last piece, a string trio by Mick Barr called “ACMED,” offered fast playing to counterbalance the slow, but it didn’t have a lot of content, either.

yMusic, a sextet that adds flutes, clarinets, and trumpet or horn to the string-trio mix, represented a step up in the quality of both performance and music. I particularly liked Sarah Kirkland Snider’s substantial “Daughter of the Waves”; was bemused by Jeremy Turner’s faux-Romantic “The Bear and the Squirrel”; and liked the drive of Judd Greenstein’s “Clearing, Dawn, Dance,” which concluded the evening. This music is available on yMusic’s CDs, but as Sirota, perhaps the best player on the stage, mentioned offhandedly, the group’s record label, the enterprising New Amsterdam Records, was devastated in Hurricane Sandy, and its CD stock was destroyed. Sirota didn’t mention the label by name, but anyone really interested in this kind of music should go check out yMusic’s Web site and think about ways to help — even if this particular concert might not have sparked as much interest as it should have.