Note: for the full suite of measurements from the SoundStage! Audio-Electronics Lab, click here.

Reviewers' ChoiceThe NAP 350 is the third and final component of Naim Audio’s 300 series to be evaluated here on SoundStage! Ultra.

Naim has an illustrious history of amplifier manufacture, but the vast majority of its power amplifiers to date have been stereo designs. Perhaps the firm’s most famous mono power amplifier was the legendary NAP 135, which first emerged in 1984 and became established as a more powerful alternative to the stereo NAP 250. In active guise, a sextet of NAP 135s could be assembled into a magnificent “six-pack” active system to drive three-way speakers such as Naim’s cavernous DBL.


I heard this system on several occasions, and it blew me away, both sonically and visually. The system didn’t sound like mere hi-fi—it was more akin to witnessing a band playing through a live PA! I’m not sure that Naim’s current flagship amplifier, the Statement, has the sheer visual impact that a six-pack system had in its day. Priced at $8499 ($16,998/pair, all prices USD), the new NAP 350 mono amplifier is the spiritual successor to the venerable NAP 135 design.

Design and engineering

As you would expect, the NAP 350 comes beautifully finished in Naim’s new-generation black aluminum-and-Perspex casing, with superbly machined heatsinks running down both sides of the rectilinear chassis. While these heatsinks are somewhat overkill for the NSS 333 streaming DAC and NAC 332 preamplifier to which they are also fitted, they are very necessary here.

Thanks to its newly developed output stage and forced-air cooling, a single monoblock NAP 350 power amplifier is capable of outputting 175W of fully regulated class-AB power into an 8-ohm load, 345W into 4 ohms, or 610W into 2 ohms. Naim claims the amplifier is capable of delivering instantaneous power of 1.7kW into a 1-ohm load—equating to a peak current output of 42A. This is weapons-grade power.


It’s interesting to note that the stereo NAP 500 DR, which sits above the NAP 350 in the range, sports an 1100VA transformer, whereas you’re getting 2000VA in total with a pair of NAP 350s. High current delivery has been a feature of Naim amplification from the very beginning, because it’s current, not voltage, that holds loudspeaker drive units in a vise-like grip. In this amplifier, power is supplied from a huge 1000VA toroidal transformer that dominates the internal space. It’s the same transformer as used for the new NAP 250; however, there are more turns of copper on the secondary winding because the NAP 350 runs at a higher voltage. In short, this combination provides enough drive for pretty much any loudspeaker you can name. It’s the most powerful amplifier Naim has ever built into one of its standard-sized cases.

The solid construction is reflected in the weight of each unit—at nearly 37 pounds, these amps are pretty darned heavy when you are trying to maneuver them onto a shelf. The case is the same size as other 300-series components, measuring 3.6″H × 17″W × 12.5″D. The front panel has the now-familiar Perspex insert with a white, backlit Naim logo in the center, and an illuminated power switch on the far right.


Working along the rear panel from left to right, there’s an IEC mains input socket, a selector switch for instant-on or automatic standby, remote sockets for system automation, a brightness selector for the illuminated logo, and a service port. A single set of high-quality, color-coded banana sockets provides the speaker connection, and in the center of the rear panel is a cover for the built-in fan. The fan only runs during periods of high workload. It is claimed to be silent-running, and proved imperceptible during my review period. To the far right is a single, balanced XLR socket, which uses a pair of Naim’s newly developed ultra-fast, low-noise, single-ended class-A buffers.

The NAP 350 benefits from Naim’s discrete-regulator power supply and eight custom-designed NA009 power transistors. Naim’s first foray into transistor development resulted in the NA001, which was followed by a long line of custom designs, leading eventually to the NA007. Codeveloped with Motorola, the NA007 was employed in the NAC 552 and NAP 500 amplifiers. The newer NA009, developed in conjunction with Semelab for the Statement amplifier, switches faster and is more linear than the NA007. The new transistor feeds less radio-frequency noise back into the amplifier circuit, which is said to result in a significant upgrade in sonic quality, a lower noise floor, and an even more rapid response to input signals. Naim Audio’s reputation for pace, rhythm, and timing wasn’t built by chance—it results from the firm’s unique engineering and design decisions.


Four NA009s drive the linear PSU, and four drive the output stage. Each is mounted on a ceramic insulator to provide an ultra-low-capacitance coupling. “Bridged amplifiers cancel second- and fourth-order harmonic distortion, leaving third- and fifth-order more exposed,” explained Steve Sells, technical director, electronics, in an email exchange. “They tend to measure with lower THD but sound more forward and this wasn’t considered desirable for the NAP 350. Heat dissipation remains the same whether bridged or single-ended circuits are used.”

The NAP 350 also features what Naim calls a Triple Transistor CCS (constant current source), which comprises two small circuits, one located at the front end of the amplifier and another in the secondary gain stage. This permits the input signal to be compared to the feedback. Sells described this to me as analogous to an old balancing scale. If the scale fulcrum is blunt or rusty, there is friction, and the scales will be less accurate and resolving. Oil the bearing and the scale is more accurate.

The unit also features Naim’s new soft-start technology, which uses a switched-mode power supply for low-powered (0.5W) standby and then switches to the linear power supply for replay when a signal is detected. This system also minimizes the risk of tripping a breaker by the high power demand of the large toroidal unit when it turns on.


Like other members of the 300 series I’ve reviewed, the NAP 350 has a number of features designed to improve sonics. The Perspex panel in the casework acts as a current divider to reduce eddy currents, and there are significant numbers of custom audio components, such as the polystyrene capacitors in the filter circuits to minimize dielectric absorption. Components directly in the signal path are through-mounted to reduce microphony, and all boards (and even many rear-panel sockets) are compliantly mounted for the same reason.

Compliant mounting is a technique that Naim has been using for decades, and new owners are often surprised that the rear-panel connectors seem to wobble a little. The aim, of course, is to prevent the interconnects and other cables that are vibrating in sympathy with the music in the room from transmitting vibration to sensitive components within the case.


Finally, there’s the matter of backward compatibility. Here, Naim seems to have thought of everything (apart from being able to switch the backlighting from white to the “traditional” green). A range of conversion interconnects have been produced to enable legacy Naim preamplifiers and power amplifiers to be used with the new generation. Not all manufacturers would be so considerate of those who are running older equipment, but Naim fans do tend to remain with the brand for decades while trading up through the range. Bravo Naim!

I was furnished with a full set of these cables to interconnect with my legacy Naim equipment. Thus, I was able to run the Naim NAC 332 preamplifier into the NAP 350 mono power amplifiers for this review, as well as my legacy NAP 250 stereo power amplifier for direct comparison. I conducted all of my listening through my reference ATC SCM40 floorstanding speakers.

Critical listening

Many audio amplifiers only come “on song” hours, or even days, after initial power-up, and I know this to be true for Naim products. It’s essential to avoid rushing to judgment too quickly before a system has warmed up. Therefore, I listened first to the NAC 332 preamplifier, powered by the optional NPX 300 power supply, into my Olive-series NAP 250 power amplifier. I have owned the NAP 250 for approximately 20 years, and it was serviced just last year at Naim. It’s a well-known quantity, and provided an ideal comparison for the NAP 350.

NaimThe 300 series takes the stage: NSS 333, NAC 332, NAP 350 (top to bottom)

I have a lengthy playlist of demo tracks I know very well on Tidal and I began with a real favorite: “Feel It Still” from Portugal. The Man’s album Woodstock (16-bit/44.1kHz FLAC, Atlantic Records / Tidal), streamed via the NSS 333. This heavenly concoction of 1960s swinging cool mated to a funky, modern dance beat is a sublime amalgam of styles. I first heard this song in a bar in Prague, Czech Republic, and I was in love with it before I’d even tasted a Pilsner Urquell.

The sheer speed and snap of the NAP 250 made this track an electrifying listen, despite the fact that it’s a studio concoction. Drums and percussive effects had tremendous pace and impact, while the vocals sounded gorgeously transparent.

Switching to the NAP 350 monoblocks brought even more agility, snap, and groove; but the biggest change was the sense of greater bass extension, which was both tighter and more controlled. The NAP 350 has a level of bandwidth available that exceeds its predecessors by a considerable margin. Drums punched a little harder and deeper, and it seemed to me that my SCM40 loudspeakers were being held on a tighter leash. Synthesized finger clicks had more presence in the room, as did the lead vocals.

This wouldn’t be one of my reviews without referencing some Scottish band or other. Deacon Blue’s superb “The Wildness,” from the band’s third album, Fellow Hoodlums (16/44.1 FLAC, Columbia Records / Tidal), is a track without audiophile pretensions, but it is a great song. Through my NAP 250, it always sounds exciting, involving, and engaging, but it can sometimes be a little strident and lightweight when played from a digital source (my original vinyl album sounds much better).


NaimThe author’s legacy Naim NAP 250 power amplifier (lower shelf)

Switching to the NAP 350s gave the piano and drums a degree more weight and warmth. This didn’t mask the detail, but it certainly made for a more enjoyable listen. Also, the timbre of the piano was highlighted more clearly. The lightweight nature of the recording was still apparent, and there will be some for whom this level of insight is a little too in-your-face. The NAP 350 monoblocks were so quick and sure-footed that on occasions I found instruments taking me by surprise—almost as if they were being played a fraction of a second earlier than I expected. I’m sure that’s just some kind of psychological effect due to the new amplifier’s incredible transient speed, which comfortably bettered my NAP 250.

It’s worth highlighting that at times I drove the NAP 350s extremely hard. Initially, I was running with the volume control somewhere between 12 and 3 o’clock. I listened like this for days on end until I discovered that the NAC 332 preamplifier came out of the box derated by default.

The ATC SCM40 isn’t an especially difficult load to drive. Its impedance drops to just under 6 ohms, but it’s inefficient by modern standards, delivering just 84dB at 1W/m. As a result, it needs a lot of power to get it to move air—those drive units are very heavy. In truth, my NAP 250 delivers the bare minimum to get the job done: the significantly greater output from the pair of NAP 350s enabled continuous high output levels with ease. I never managed to drive the monoblocks into thermal shutdown, which occasionally happens with my NAP 250. The NAP 350s got pretty warm, but they were completely stable. Furthermore, the sonic character didn’t change with output level, lending the NAP 350 pair a sense of effortlessness that my NAP 250 simply lacked.


Nowhere was this sense of effortless power and scale more evident than in Georg Solti’s masterful recording of Beethoven’s Symphony No. 9 with the Chicago Symphony Orchestra (16/44.1 FLAC, Decca Music Group / Tidal). Here, massive orchestral and choral forces are given full rein in the large acoustic space of the Krannert Center for the Performing Arts at the University of Illinois. Recorded in 1972, this is one of the best-sounding recordings of the Ninth I have ever heard. Mobile Fidelity agrees, because the audiophile label chose to reissue it.

This recording is extremely demanding of any system, and the fully assembled Naim 300 series rose to the challenge admirably. The system’s significantly greater bass power and slam, compared to my resident NAP 250, meant that the rolling timpani thundered and shook the air in the room. It wasn’t all shock and awe, though. During the choral section of the fourth movement, there was a palpable sense of the hall’s acoustics, while the massed voices of the choir had excellent transparency at all times.

The orchestra itself was presented in a wide acoustic, with considerably more soundstage depth than via the NAP 250. I’ve remarked before that one of the biggest leaps made by the new-generation Naim amplifiers is their ability to project a convincing and tangible soundstage with genuine depth—the Earth is no longer flat! Massed strings on this recording sounded sublime, with the violins and violas in the first movement soaring over a majestic foundation of cellos and double basses. When the full 300 series was playing, I began to question if I had ever heard this recording sound better through my loudspeakers. The NAP 350s had the effect of making my ATCs sound even bigger than usual, their gravitas more palpable, their soaring dynamics more rapturous.


This has been a lengthy and complex trilogy of reviews. I’ve spent two months living with the Naim 300 series, and listened to each element in various combinations for hundreds of hours during that time. This has resulted in over 9000 words of technical and audio description, designed to inform and entertain.


Make no mistake, this is the most visually attractive series Naim Audio has ever launched, but it’s also very clear that the firm has advanced its state of the art sonically and ergonomically, too. I loved the way these NAP 350s managed to combine the firm’s traditional strengths of pace, rhythm, timing, and dynamics with newfound abilities in imaging, tangibility, and stage depth.

The NAP 350 fits into this new range perfectly, like Audrey Hepburn slipping on a cocktail dress—they’re made for each other. The NAP 350 has superb drive, impressive bandwidth, detail, and power, and is capable of maximizing the performance of any loudspeaker that you might care to use.

I love that the system’s remote control triggers its backlight as soon as you move it, and that it’s omnidirectional. I adore the feeling of reliability and solidity I get with Naim products: secure in the knowledge that even 20 years down the line, the firm will still be around and willing to service and support my equipment. In a world of disposable electronics, this kind of longevity is deeply reassuring.

NaimNaim Audio’s servicing and repair facility

Perhaps more importantly, this new range displays a little more of the mojo that characterized the earlier series of Naim amplification. When listening to this complete system, there was a visceral energy that I found highly addictive, capturing much of the thrill and energy of live music. This certainly isn’t an amplifier that will cosset you, or blunt the dynamics and impact of the original performance. For some, it might be a little too much; for others, it will be perfect, because it embodies everything that Naim has ever stood for.

This is an audio ecosystem that makes playing music exciting again, and will lead you to spend as much time in record shops or listening to music as you did when you were 16. You’ll sometimes arrive at work looking haggard after a late night spinning just a few more tracks. Your boss won’t like it, your bank manager won’t believe it, and your mother-in-law won’t understand it.

I can’t think of any better reasons for buying it. Turn on, tune in, drop out . . .

. . . Jonathan Gorse

Note: for the full suite of measurements from the SoundStage! Audio-Electronics Lab, click here.

Associated Equipment

  • Turntable: Michell GyroDec turntable with SME Series IV tonearm and Audio-Technica ART20 cartridge.
  • Phono preamplifier: Trichord Research Dino Mk 3 with Never Connected Dino+ power supply, PS Audio Stellar phono stage.
  • Streaming DAC: Naim Audio NDX, Naim NSS 333.
  • CD player: Naim CDI.
  • Preamplifiers: Naim NAC 82, Naim NAC 332.
  • Power amplifiers: Naim NAP 250.
  • Power supplies: Naim HiCap, Naim NPX 300.
  • Loudspeakers: ATC SCM40.
  • Power: Dedicated 100A mains spur feeding two Graham’s medical-grade, six-gang power blocks; Naim Hydra; Naim Power-Line Lite.
  • Cabling: Chord Company Sarum T loudspeaker cables, Naim NAC A5 loudspeaker cables, Naim interconnects on all Naim amplification, Chord Co. Sarum T Super ARAY XLR, Chord Co. SignatureX Tuned ARAY DIN-RCA, Chord Co. SignatureX RCA-XLR, Chord Co. EpicX ARAY RCA. Chord Co. Chameleon interconnects for phono stages, QED interconnects for secondary sources.

Naim Audio NAP 350 Mono Amplifier
Price: $8499 each.
Warranty: Five years, parts and labor.

Naim Audio Ltd.
Southampton Road
Salisbury SP1 2LN
United Kingdom
Phone: +44 (0)1722 426 600


North American distributor:
Focal Naim America
156 Lawrence Paquette Industrial Drive
Champlain, NY 12919
Phone: 1-800-663-9352