Music in the Round #83: ATI & Monoprice 3-Channel Amplifiers Page 2

In direct comparisons with Parasound's Halo A 31 three-channel amp, the AT543nc seemed to offer more lower midrange, less treble, marginally more richness, and a slight tilt in balance. The ATI seemed to present a bit less air and space, but I can't say whether the Parasound is any more accurate in this regard. However, all that was noted only briefly upon switching from one amp to the other. The ATI and Parasound both had smoother, more enjoyable sound with Focal's Sopra No3 speakers than did the Classé Sigma Monos, which unsympathetically revealed some upper-midrange glare in some recordings.

I also tried the AT543nc's unbalanced inputs, using Cardas Cross 10m cables. The overall level was down about 6dB, as expected, but the sound quality was unchanged.

Conclusion: I am completely taken with ATI's AT543nc. It seemed to do everything right, and didn't get in the way while communicating the elements and the spirit of the music. I wish I'd had on hand its older cousin, the Theta Dreadnaught D, for direct comparisons, but given the Theta's higher price ($7099.95) and weight (90 lbs), any outcome could not possibly blemish the $3295, 57.5-lb ATI AT543nc.

Monoprice Monolith 3 three-channel power amplifier is a popular website—a place where those in the market for cables, connectors, switching devices, or associated tools know they can find what they're looking for, and at reasonable prices (footnote 2). Monoprice's inventory is encyclopedic, and they offer great how-to aids for novices—when I rewired my cable TV system, I relied on them for the cable, connectors, tools, and guidance. Given their success, it's not surprising that they've branched out into more sophisticated offerings, such as their well-priced, high-speed, active HDMI cables and A/V products. Their Monolith line of power amps is, for them, a big step into a new market.


The Monoliths are 200Wpc class-A/B amplifiers offered in versions for two, three, five, and seven channels. All models come in identical cases measuring 17" wide by 7" high by 13.3" deep; the only distinguishing features are the model number on the front panel, the number of connectors on the rear panel, and the weights, which range from 48 to 94 lbs. The prices range from $999.99 (two channels) to $1499 (seven channels). Like Goldilocks, I chose an in-between model, the three-channel Monolith 3, at 57 lbs and $1099.90.

Description: The Monolith 3's appearance impresses as cleanly designed and executed. The main housing is rigid, with a central, illuminated On/Standby switch on the faceted faceplate. On the right of the sturdy rear panel, from bottom to top, are an IEC power inlet, the main power switch, a ground terminal, and a 12V trigger input. The rest of the rear panel is occupied by an unbalanced input jack (RCA) and a pair of multiway speaker posts for each of the three channels. The speaker terminals are finger-friendly, but I plugged my cables' bananas right in. The gold-plated RCA jacks are firmly mounted on the rear panel, not on internal PC boards, from which they might be loosened by normal use. My only cavil is that the sheet metal of the case seemed a bit thin compared to the rest of the hardware. It didn't rattle or buzz in use, but it might benefit from the internal application of some damping material.

The Monolith 3's specifications are impressive. Its FTC full-bandwidth power output is 200Wpc into 8 ohms or 300Wpc into 4 ohms. Total harmonic distortion and intermodulation distortion are each less than 0.03%, and the A-weighted signal/noise ratio is greater than 120dB, all referred to full output power. (In addition to listing the specs on their website, Monoprice supports them with an eight-page document of test results.) The Monolith 3 weighs 57 lbs, most of that weight due to its single 1025VA toroidal power transformer. Unfortunately, the toroid is at the front left corner of the case; the uneven distribution of weight makes it a bit harder to heft the Monolith 3 than other amps of the same weight.


Since the Monolith 3 lacks balanced (XLR) inputs, I dragged from the back of my closet some 10m-long Cardas Cross cables terminated with RCA plugs and used them to link the Monoprice to my Parasound Halo P 7 7.1-channel preamplifier.

Stop a moment and reflect on all I've just described. The Monolith 3 is a well-constructed power amp with excellent specs and all the power that any normal listener with a trio of normal speakers to power can use. If it sounds good (it did) and doesn't blow up (it didn't), it's a bargain at only $1099.90. And at this point, many of you might just stop reading and buy one.

For the rest of you, I press on . . .

Listening: The music flowed. Despite the length of the unbalanced connection, I heard no problems with noise. The sound was right and full, with an emphasis on the lower end of the audioband. Remember, unless I'm reviewing a loudspeaker, I use the default target curve of Dirac's Live room-correction software for all of my auditioning and listening. So when I say that I hear a change in balance with any new component other than a speaker, that's based on what I hear relative to the component that the review sample has replaced, and not on any absolute reference. That said, the Monolith 3 sounded a bit warmer than any of the other amps I have on hand, and while this will be a positive for many, I am not among them.


Despite that, the Monolith 3's reproduction of tonalities was more than acceptable, and its soundstages, in stereo or in multichannel, were ample, wide, and deep, with voices and instruments stably positioned on them. The Monoprice's bass extension and power were formidable, and its midrange and treble seemed smoothly extended. I played all my standard test tracks, ranging from solo voices and instruments to raging massive forces. Through the Monolith 3 they sounded clean, unstrained, and rich—almost beyond criticism. Overall, the Monolith 3 was conducive to relaxed, extended enjoyment of music—until I put on my critic's cap and looked for trouble.

The troubles I had with the Monolith 3 were its lacks of air and space, and of the crisp delineation of individual voices and instruments. Given the amp's power capability, this did not correlate with volume level—the Monoprice sounded much the same at all levels. Rather, it seemed to correlate with instrumental complexity, and became more noticeable as the size of the ensemble increased. Some of this, undoubtedly, had to do with the amp's spectral balance—to be sure, the Monolith did not suffer from any excess brightness that might have emphasized space and detail. Well-recorded solo guitar and violin seemed a bit warmer than I am used to hearing from my system.

When I played that spectacular recording of Matheson's String Quartet, each of the four instruments sounded clear, but there was less differentiation of them when they all played together, as in the opening chord. And take almost any of the Channel Classics recordings by Iván Fischer and the Budapest Festival Orchestra—eg, Tchaikovsky's Symphony 6 (SACD/CD, CCS SA 37016)—which are notable for their realistic documentation of the sound of an orchestra in a sympathetic acoustic: Through the Monolith 3, the orchestral chords sound compacted and homogenous, and less like an ensemble of players.

Conclusions: Perhaps I'm being unreasonable in judging this powerful, inexpensive, more-than-capable three-channel power amplifier by absolute standards. The Monoprice Monolith 3 was really easy to listen to, and, at the risk of insulting home-theater enthusiasts, it did a great job with the Blu-ray of Star Trek: Beyond. It might be more suitable with brighter speakers, or in rooms with insufficiently sound-absorbing furnishings. But the Monolith 3 is hard to recommend to critical music listeners who've been scrupulous about their systems.

Coming Around in the Round
As I write, the 2017 Consumer Electronics Show is just around the corner, and it seems that lots of interesting things are on their way: new multichannel server/players from Baetis and Fidelizer, exaSound's new e38 DAC, and three-DAC stacks for multichannel from Playback Designs and Mytek. And a surprise.

Footnote 2: Monoprice, 11701 Sixth Street, Rancho Cucamonga, CA 91730. Tel: (877) 271-2592. Fax: (909) 989-0078 Web:

Odin 412's picture

Thanks for reviewing some power amps at less-than-insane prices! The Monoprice amp sounds like a huge bargain. Great sound at around $1K? I'm interested - I only wish that the amp was a bit smaller. I'm also not sure how "conducive to relaxed, extended enjoyment of music" can become a negative, but to each his or her own.

Kal Rubinson's picture

"Conducive to relaxed, extended enjoyment of music" is not a negative but it does not encompass the full range of my listening experiences.

billtheblizzard's picture

Mr R. reproaches the Monolith as "conducive to relaxed , extended enjoyment of music." He writes "(it) does not encompass the full range of my listening experiences."

Would that full range of listening experiences, by corollary, extend to the obverse of "relaxed, extended enjoyment of music" -- tense, brief and displeasurable? For that is what Mr. R seems to imply. True stereophiles, it seems, listen to music not only for mere pleasure, for that would be bourgeois and pedestrian, but also to wallow (as a masochist) or revel (as Nietzschean Superman) in discomfort, anxiety and unease.

True seekers like Mr. R. understand that a good HiFi set up will be analogous to putting on your hair shirt or flagellating yourself like a devout penitent. One might say: the greater your suffering the superior your system. That which best reproduces nails on a chalkboard is next to godliness sayeth the wise.

"ATI makes a wide range of audio devices under its own name, as well as under brand names it has acquired, including B&K and Theta Digital, as well as SAE. In addition, it has produced amplifiers for many other companies which I will tactfully not list."

That's funny because I thought the job of a reviewer/journalist was to be as transparent and informative as possible. MR R. though must undoubtedly have the best reasons for his policy of obscurantism. It would be jolly arrogant of the Stereophile reader to expect the reviewer to risk embarrassing certain manufactures by revealing the OEM behind a given product and, de facto, the all too obvious massive mark up that comes with the cache of a big name. Heaven forbid the reader be more informed at the expense of a reviewer daring to be untactful! Why should the unwashed readership expect full disclosure from anointed gatekeepers like MR. R?
In the same diplomatic-let's-not-rock-any-boats-"tactful" vein, Mr. R. also does not mention that ATI is the OEM for the Monoprice Monolith Amps. Because how could anything be more tactless than revealing the provenance of a made in the US, $1,000, 200W, class AB amplifier, exhibiting excellent measured performance (see review in sister publication Sound and Vision)that commits the sin of making good music for so few dollars. Strike one: Monoprice (shush about ATI dammit!)Strike two: it's really affordable (What! The peasants have a better amp than my gold plated piece of audio jewelry from Geneva?). Strike three: The amp sounds too nice and fails to give aural ascetics the hair shirt feel they crave and demand.

Kal Rubinson's picture

First, I do often listen to music that is intense, disturbing and aggressive. The Monolith tends to soften those attributes and, thus, it does not serve all of my listening needs.

Second, this is a review of the Monolith and not investigative journalism. ATi makes a wide range of OEM products over a wide range of prices and one should not suspect that they are equal nor that they are intended to be. The Monolith is a remarkable product for the price regardless of its source.

HammerSandwich's picture

Kal, I doubt you could lift such a beast. Perhaps 950VA?

Kal Rubinson's picture

Yup. Almost 1kvA.

HammerSandwich's picture

...your conclusion about the Monolith seems more absolute than warranted by:


So when I say that I hear a change in balance with any new component other than a speaker, that's based on what I hear relative to the component that the review sample has replaced, and not on any absolute reference.

Especially when auditioned with only 1 model of loudspeaker!

System synergy makes sense, but it works only when we remember that we always evaluate systems.

Kal Rubinson's picture

Good point but there were several previous amps around for contrast: ATI, Classe and Parasound. It was a consensus.

ToeJam's picture

Mr. R., I understand the differentiation you make between the subtle (or otherwise) variances in how the Amps sound relative to each other. I hear you saying that the Monoprice sounds good and pleasant, but lacks some of the refinements the ATI and Parasound present.

I appreciate your careful articulation of what you discerned because it helps me decide if I want to invest more to obtain the specific improvements you describe.

Kal Rubinson's picture

Almost all the stuff we play with is pretty good and screaming about HUGE differences is rarely called for.

NiviM's picture

Hi Kal,
How do you compare the sound of the Nad M27 to the ATI AT543nc ?

TJ's picture

... when I ordered a new ATNC522 stereo amp after reading your review. Within days I discovered three product defects, all intermittent (mechanical transformer buzz, protection circuit instability during normal playing, occasional ground loop) in a high end system that's always been completely stable and has never had a grounding problem. It's possible of course that these intermittents might be the consequence of rough handling during shipping. I was also disappointed to find an IC op amp buffer stage (not discrete class A like Nord Acoustics and others) and with B&W 805 speakers, more than a "slight tilt" in the tonal balance that you noted with your speakers. Too bad, it seemed promising.

JRT's picture

While I do appreciate Kal's opinion, appreciate his sharing his perspective, and his efforts in reviewing interesting things in his recently ended column, I think that reviews of audio electronics and loudspeakers should be both subjective and objective, so this review of the ATI amplifier remains half of a review without the associated objective measurements.

This family of amplifiers using Hypex NC500 amplifier modules is still a current product, and seems worthy of a deeper dive in another review, maybe for a larger segment of Streophile readers in two channel configuration. I would like to see JA1's measurements of an ATI AT52xNC and/or AT54xN, regardless the number of channels, bundled with another review.