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ATI AT6002 Amplifier Review

Home Theater
by Jerry Del Colliano

There is a wine maker in California known as Jim Clendenen who makes some of most fantastic Chardonnays in the central coast under the brand Au Bon Climat, as well as under his Clendenen Family Vineyards moniker. He is also contracted with legendary wine stores like Wally's Wines to make their house brand. Roy Yamaguchi from the Hawaiian chain of Roy's restaurants has been known to use Clendenen's wines as the restaurant's premium house Chardonnay. He's the star wine maker backing the bars of the best restaurants out there.

Morris Kessler is the same guy for amplifiers. With 50-plus years of manufacturing experience, it could be argued that nobody makes a better amp for the dollar than Morris. Other companies seek out his help with both design and manufacture, including but not limited to the Harman brands, Outlaw Audio, Lexicon, Datasat, and many others over the years. Morris also owns brands like SAE, Theta Digital, and B&K and makes many of their amps.

The ATI AT6002 is Morris' signature stereo power amplifier, part of the ATI AT6000 Signature Series, rocking 300 watts/channel into eight ohms in a stereo configuration for $3,995. It can be purchased direct or through dealers and/or custom installers. If you need more channels of power, ATI has you covered with the ATI AT6003, ATI AT6004, ATI AT6005, ATI AT6006, and ATI AT6007, which as you may have guessed are the three-, four-, five-, six-, and seven-channel brothers of the stereo 6002.

ati at6002 audio power amplifier review home theater

The ATI AT6002 is a mean amp. Its fully balanced design uses current feedback with a single input stage and dual-differential output stages to increase amplifier speed (slew rate) and reportedly reduce noise by upwards of 50 percent. The ATI AT6000 Series amps use dual DC servos to deal with issues of DC offset. You actually have to plug this amp into the wall twice, which you will gladly do when you get your first taste of the sound.

ATI offers a seven-year transferable warranty, which is quite favorable to the consumer. The ATI AT6000 Series amps report 0.03 percent THD at eight ohms, 20 Hz to 20 kHz with all channels driven to the max, thus the amp has the headroom for today's best formats, be it Dolby Atmos, HD music files, or uncompressed 7.1 soundtracks from Blu-ray. All ATI 6000 Series amps use dual toroidal transformers, dual power switches, and dual AC power chords, thus they are truly dual mono amps in one chassis. The AT6007 reportedly performs even better when given two unique 20-amp circuits to provide its power. That might be a little bit of overkill for the ATI AT6002, not that overkill ever goes out of style when you are talking about big, audiophile-grade amps.

The ATI AT6002 amplifier measures 9.5 inches high, 17.25 inches wide, and 18.5 inches deep, with a 19-inch faceplate suitable for rack-mounting. Under normal circumstances, I'd prefer to bolt the ATI amp right into my rig; however, for this review, I swapped out my measly (it's really not measly) pure Class A Pass Labs XA30.5 amp with the 300-watt Class AB ATI amp in my office rig. The ATI amp powered Focal Diablo Utopia Diablo speakers and enjoyed a signal fed from a Benchmark DAC1 PRE, with sources like an Apple Mac Pro tower, an Oppo BDP-103, and beyond. Cabling was Transparent Reference for analog, speakers, and most digital cables.

ati at6002 rear audio power amplifier

The Hookup

Installing an ATI AT6002 amp couldn't be much easier. Open the box. Pull off the plastic. Be careful not to hurt your back lifting the sucker, especially if it's one of the multichannel amps (the ATI AT6000 Series amps weigh between 86 and 136 pounds, depending on the model). Plug in your XLR cables (remember, this is a balanced amp, thus you will want to enjoy it in a fully balanced system), plug in the power cables, attach the speaker cables, and you will be ready to go. I did have a little bit of an issue getting the spades of my Transparent speaker cables into the back of the ATI AT6002, but with a little finesse, I was able to get it going. Top cable companies like Transparent are glad to re-terminate your cables if you make an upgrade to a new amp. Often you just need to send them back, and they will take care of you as your system demands.

Heat is always a consideration with big power amps; but, in this case, I couldn't get the ATI AT6002 to run very hot even under heavy abuse. Perhaps in a more enclosed rack, the ATI AT6002 will run hotter. Compared with other amps in the price category and above, though, the ATI AT6002 runs as cool as a cucumber.


We can and will talk about audio jewelry later; but, when auditioning an amplifier of this classification, you want to get to the listening process as fast as you can. I kicked off my evaluation with "Para Sempre" from the latest Thievery Corporation album Saudade ripped at 1440 AIFF. This fast-paced yet loungy Brazilian-jazz-inspired track jumped right out at me with an immediacy that seriously caught my attention. Bass was well defined. The female vocals were sweet -- not Class-A amp sweet, but 90 percent of the way there. The depth of soundstage was notable. With this much power on 94dB-efficient Focal speakers, it felt like having a V12 power plant waiting for you to stomp on the accelerator. Just give me a second until I pull onto the freeway, OK?

I then evaluated at the ATI AT6002 through what I call "The Jimi Standard" -- that means if a system/component/speaker doesn't sound good with Jimi Hendrix, then it likely sucks and shouldn't be bought. I cued up "Gypsy Eyes" from the Electric Ladyland CD. Obviously, the age of the recording was evident compared with the previous track, but what was notable was the depth of soundstage. Yes, this is a quiet amp, as Morris went to great lengths to refine every detail he could for his reference offering. The result is not only an ability to resolve the excitement of a left-handed Fender Stratocaster played by the greatest guitar player of all time, but also the ability to remarkably reproduce the depth of a recording made during a renaissance period for rock-and-roll music.

Moving forward a few decades to "Sara's Smile" from Hall and Oates' Greatest Hits Rock and Roll Soul (CD, via the Oppo BDP-103), I could hear from the first breath of the track that it was recorded on analog master tape, and that "warmth" was the only noise I heard. Daryl Hall's voice was quickly presented front and center with some of the best imaging I've heard. In comparison with my reference Class-A Pass Labs XA-30.5 amp, the ATI has the Pass Labs beat in the power department and is super quiet, but the Pass Labs amp resolved the xylophone and background strings with more subtlety. When John Oates kicks in with the background vocals, you get a lot of finesse - perhaps some of the closest I've heard under $10,000 from a non-Class-A amp.

Moving to No Doubt's "Hella Good," a more modern track with lots of dynamic range, allowed me to stomp on the accelerator a bit musically. The deep bass notes were extended yet quick. The electronic programming/production, slightly in the background of the mix, resolved itself beautifully, as it's simply obvious that you have such huge reserves of power waiting for you to use and/or abuse whenever you want. The point where other amps fail on this track is the transition into the chorus. That's not the case with the ATI AT6002, as it just sort of laughs off "Hella Good" as being a demanding demo track. OK, you want a fight, I will give you a fight...

I moved on to Pink Floyd's The Wall (disc two in 1440 AIFF from the Mac Pro). On the mysterious "Vera," the openness and quiet of the ATI 6002 was compelling. Roger Water's voice beamed above the gorgeous representation of the musical bed. With the segue into the bombastically orchestral "Bring the Boys Back Home," the ATI AT6002 pretty much said, "Finally, I can stretch out a little bit." The chorus resolved wonderfully over the top of the full orchestra, while Water's vocals remained ever-present. You get both power and finesse with the ATI AT6002 that historically required spending a lot more money to get a top-of-the-line audiophile amp.

With Transformers on Blu-ray, the scorpion fight scene brings in as much Michael Bay action as you possibly can handle, complete with an automated, pissed-off mechanical scorpion, bomb blasts, thousands of rounds of gunfire, drones in flight, and even a failed call to a customer service agent in India. The spooling engines of the fighter planes sounded energized. The cliché military orchestral music in the background even sounded good. In the cacophony of such an over-the-top bombastic demo, the ATI AT6002 didn't really crack a sweat, nor did it miss a beat.

ati at6002 front audio power amplifier

The Downside

It's time to talk about audio jewelry because, when you get into top-of-the-line audiophile amplifiers, that's part of what you are buying. With the ATI, you are getting the Pontiac Aztek of industrial amp design. It's a black box with Morris' signature and what I think is a pretty bland if not ugly logo. There aren't fancy heat sinks, as the amp doesn't need it. Utilitarian rack handles adorn the front of the amp, and a modest but non-dimmable blue light notifies you that the power is on. The ATI AT6002 is about as plain-Jane as you can get when it comes to goodies, and that's exactly why it costs $3,995 and not $10,000 for the stereo amp.

Does the performance of the ATI AT6002 command a fancier wrapper? Perhaps, but that's missing the point. This is the world's leading contender for a bang-for-your-buck amplifier. It's the type of amp that you put in your rack and control via a trigger, not the type of amp that you park on amp stands behind your speakers. If you want the later, there are a dozen companies that make a 300-watt amp that will meet your needs -- you just might need to spend $10,000 to get your hands on one.

Comparison and Competition

I guess in the world of seven-channel amps, you could compare the AT6007 to the Outlaw Audio 7900, both made by Morris Kessler. In the world of stereo amps, I made a pretty odd comparison to a 30-watt pure Class A power amp from Pass Labs in the XA30.5; but, at $5,500, it's in the price category, and the two fight it out nicely in terms of fine details, despite the fact the Pass Labs amp is a physical beauty in comparison. Krell, Classe, Mark Levinson, and all of the other blue-chip audiophile companies have very worthy offerings, but all are nearly twice the price (if not higher) of the no-frills ATI 6002. From my listening tests of other amps, you have to look to the likes of the Krell 402e or my former reference amps, the Classe CT-M600 mono blocks (man do I miss them) at around $12,000 per pair and packing 600 watts per channel, to get notably more amp. That's a lot more money for the next level up.


A lot of amp designers -- from Dan D'Agostino with the Aragon 4004 to Nelson Pass with the Adcom GFA-555 -- have tried to make the best-value audiophile amp. Today, I think Morris Kessler owns the crown. The ATI AT6002 is one of the most powerful, resolute, quiet, and musical amps that you can lay your ears on, even though you can spend a lot more money on others that go to that next level. Is it time to get carried away and say it's the best amp ever? No, that would be a foolish mistake. What you could say is that, dollar-per-watt, you might not be able to find a better amp today. The ATI AT6002 is a wonderful performer and a stunning value. It is very bare bones yet performance-oriented in its approach, just like the man whose signature is on the front. Don't let the comparably low price fool you, as this amp is for real. Its only real competition are amps from the big boys costing nearly twice the price.