Description
Why the AT522NC?
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Modular flexibility: Available from 2 to 8 channels (200 WPC @ 8Ω, 300 WPC @ 4Ω).
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Hypex N-Core® modules + ATI input stage: Delivers state-of-the-art performance.
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True high-end specs:
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<0.02% THD
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–123 dB SNR
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Full FTC Power Rule ratings
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Smart power management: Microprocessor-controlled soft start, automatic AC voltage recognition (120/230V), and auto-sleep circuit.
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Cool, efficient, compact: 90% efficient Class D topology = less heat, smaller chassis, lower cost.
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Peace of mind: 7-year parts & labor warranty.
ATI’s Secret Sauce: Custom Input Stage & Linear Power Supply
What sets ATI’s Class D amplifiers apart from the pack isn’t just their use of Hypex N-Core® modules — it’s the way Morris Kessler integrates them. Each AT522NC amplifier features a proprietary ATI input buffer stage that ensures maximum signal integrity, tonal neutrality, and musicality. Most Class D amps rely solely on the off-the-shelf module, but ATI adds its own engineering layer to elevate performance into true high-end territory.
Pair that with a massive linear power supply — instead of the lightweight switching supplies found in competing Class D designs — and you get rock-solid current delivery, tighter bass control, and the effortless dynamics that ATI amps are famous for. This unique combination of ATI input stage + linear power is why these amps sound more like the best Class AB designs, while retaining all the efficiency, low heat, and compact size of Class D.
What Experts Say
“They offer everything one would want: powerful dynamics and uncolored sound… I liked these amps so much, I actually bought them as an upgrade to replace my Parasound A 51, a well-established favorite. That’s quite an accomplishment… they represent extraordinary value.”
— David Vaughn, Sound & Vision
“The ATI AT522NC seems like a solidly built amplifier… Overall, I can recommend the ATI AT522NC stereo amplifier.”
— Amir M., Audio Science Review
“The AT522NC woke up the Revel M20’s, adding fun to many familiar recordings… Clearly capable of delivering room-shaking bass. This is not the case of Class D being dark or lacking bass — the AT522NC proves otherwise.”
— Rich B., Audioholics
“ATI has one refinement on which practically every authority agrees: fully differential construction… It cancels out noise, operates at twice the speed of an ordinary amp, and is rare even among high-end audiophile amps.”
— Brent Butterworth, Home Entertainment & Design
“I got everything I needed in an excellent pair of amps at a great price, made locally in CA, USA. Quality construction, careful engineering, and thoughtful features… These are well worth the $$$$.”
— AVS Forum Reviewer
More Power. Less Heat. Better Sound. That’s ATI.
David Vaughn, Sound & Vision, May 2017 –
David Vaughn, Sound & Vision, May 2017 – December 15, 2020
“As you can probably tell, I really liked these ATI amps. They offer everything one would want: powerful dynamics and uncolored sound. Given their Class D architecture, they run extremely cool compared with my main reference Class A/B amp—which isn’t such a benefit in the cold of winter but will be a godsend come summer. And now I’m really looking forward to summer because I liked these amps so much, I actually bought them as an upgrade to replace my Parasound A 51, a well-established audiophile/videophile favorite that has been my reference for many years and through many other amplifier reviews. That’s quite an accomplishment for these ATI amps, but I feel confident in saying they deserve to be placed in the same high-end category—and they represent extraordinary value to boot. I can’t recommend them enough.” David Vaughn, Sound & Vision, May 2017
Amir M, Publisher of Audio Science Review, Nov 2019 –
Amir M, Publisher of Audio Science Review, Nov 2019 – December 15, 2020
“The ATI AT522NC seems like a solidly built amplifier based on Hypex NC500 modules. ATI builds amplifiers for many other companies and this competence shows up in this review. Performance is of course limited by what the NC500 module can do. Use of linear power supply defeats the size and weight advantages of common class D amplifiers. It may provide better peak power rating — something I wanted to test but forgot. 🙂
Overall, I can recommend the ATI AT522NC stereo amplifier.” Amir M, Publisher of Audio Science Review, Nov 2019
Rich B, Audioholics May 2019 –
“The AT522NC woke up the Revel M20’s, adding fun to many familiar recordings. Female vocals lifted, presenting a great emphasis on dynamics and sibilants. The dynamic and hard-mic’ed vocals on Sarah Jorosz “Undercurrent” (HDTracks 96/24) are not forgiving on any system. Driving the Salon2s, the AT522NC drum strikes hit hard, demanding attention, clearly capable of delivering room-shaking bass from the Salon2’s woofers. The AT522NC is no lightweight amplifier but the weight and heat reduction are benefits worth considering. ATI’s NCore amps are popular for Home Theater. Judging from ATI’s styling, they are clearly targeting that market.
Class-D has been described as dark and often lacking bass when driving difficult loads. This is not the case with the AT522NC.”
Rich B, Audioholics May 2019
Brent Butterworth, Home Entertainment & Design – December 15, 2020 –
“ATI has one refinement on which practically every authority, from the ultra-conservative “everything-sounds-the-same” engineer to the rarified audiophile, agrees: fully differential construction. Author G. Randy Slone, the expert who wrote High Power Audio Amplifier Construction Manual, describes differential construction as the “Cadillac” of amplifier designs; consider this accolade the highest level of compliment and forgive his limited familiarity with luxury automobiles.
Intimidating as it may sound, fully differential construction is fairly easy to understand. A differential (or mirror-image) amplifier uses two identical amplifier circuits, where only one was used before. One amplifies the positive half of the audio signal; the other amplifies the negative half. This design cancels out noise that ordinary amplifiers would pass on to your speakers. It also operates at twice the speed of an ordinary amp. Of course, doubling up on circuits adds considerably to the cost of manufacturing, so fully differential construction is rare, found mainly in very high-end, audiophile-oriented amps.” Brent Butterworth, Home Entertainment & Design
AVS Forum – December 15, 2020 –
Audio Visual Science Forum Dec 2019
ATI’s “True Balance” Differential Design Architecture
“Getting back more specifically to amps, I really need amplifiers that can do certain things for me, and the ATIs have all that, plus more. I want to go full balanced instead of single ended, and ATI handles that, plus the “true balance” differential design architecture of the amp really fits the bill for me. I want lots or headroom, and with three 200W channels per amp being fed off two gigantic toroidal transformers, there’s no bottom to this well–or at least I can’t find it.
About that 200W/channel–it’s not really true. Are they liars? Well, no, my actual measurements find them to be running about 210-220+W/channel, all channels driven from full range 20Hz to 20kHz noise. So it’s not your typical, lame 200W/channel with one channel driven only at 1kHz.
A nice surprise is the soft start circuitry. I have a single 20 Amp circuit dedicated to this system, and with the amps connected via DC triggers to the pre, a push of the on button brings the whole system up in an orderly fashion, without pops, thumps, thrown breakers, or house wide brown outs. I can take the Niles IPC6 sequencer right out of the system.
All in all, I got everything I needed in an excellent pair of amps at a great price, made locally in CA, USA. Plus, I didn’t pay extra for what I didn’t need: fancy billet Aluminum front, big prestige brand name, expensive marketing campaign, and huge overhead. Instead, when looking at them up close, I can see the quality construction, the attention to detail, the careful engineering, and the thoughtful, useful feature set.
These are well worth the $$$$.”