AOM Logo April 2008

The NuForce Reference 9 V2 Special Edition Monoblock Power Amplifiers

Martin Appel



NuForce came on the scene as one of an early group of companies utilizing digital technology in the design of their amplifiers. As in any new technology, there were some problems that became apparent in the first products that had to be addressed. It was not only NuForce, but others as well, that ran into some difficulties with their designs: RFI interference, extreme cable sensitivity, high frequency thinness, among others. As with any new technology, problems developed and were addressed. Solutions were incorporated as soon as they could be and the 9V2-SE represents the latest development from NuForce.

The audiophile community’s initial response was not favorable towards digital amplification. As various problems were addressed and solved, acceptance has grown begrudgingly. The Reference 9V2 SE represents the latest iteration from NuForce that purports to address any remaining issues that one might have with digital amplification. My colleague, Henry Wilkenson, reviewed their Reference 8.5 monoblocks and was quite impressed. After much discussion with Henry and hearing the “buzz” about their amps, I decided to investigate their latest effort, the Reference 9V2-SE. I contacted Jason Lim, CEO at, NuForce and he was kind enough to send me four monoblocks. Why four? My Wasatch Acoustics Musina speakers are two way designs that require bi-amplification, requiring two monoblocks per speaker (NuForce doesn’t make a stereo version).


I’d like to write a few words about their technology and design. NuForce calls their amplifier an “Analog Switching Amplifier TM”. Now, I’m not an engineer, but according to their manual, it works on the principle that an audio signal modulates a power oscillator and is then reconstructed with the use of a filtering system. Apparently, the benefits derived from this methodology include extremely wide bandwidth (20Hz to 50kHz flat and extend to 90kHz), virtually, no phase shift in the audible frequency range and an extremely high damping factor. All this results in an incredibly quiet and distortion free amplifier. RMS Power output is 190 watts/monoblock at 8 ohms and peak power is 325 watts (20msec hold time) and at 4 ohms, the numbers are 300 watts RMS and 650 Peak, respectively. This is all coming from an amplifier weighing in at a miniscule 8.5 pounds. For a more in depth technical description, see their website,

The units came in a metallic copper red finish that I found very attractive and worked in concert with the cherry wood cabinet in which they were housed. They also come in black and silver. The rear panel has the usual on/off switch (wish all mfrs would put these on the front) with an IEC socket for a power cord and a toggle switch for choosing single ended or balanced operation. WBT NextGen RCA sockets are used along with Eichman cable pod binding posts for your speaker cables. This review was performed using Acoustic Zen’s Absolute balanced interconnects.

I installed the 9V2-SE’s in place of my two Innersound iPower 330 stereo amplifiers. All four NuForce amps were less than the size of one of one of my Innersounds and weighed less, too. Of course, this arrangement requires two more power cords. Talk about saving shelf space. Now that’s all very nice but how did they make the system sound? Has NuForce digital amplification come of age?


I burned in the units for about 150-200 hours of continuous music using the provided power cords and then started some serious listening and evaluating. My first response was amazement. These amps were dead quiet. No grain. No hash. Just dead quiet. When music poured forth, it was so palpable. The sound staging abilities these amps exhibited was dramatic. The separation of instruments in the recorded venue added to clarifying the complexities of the music. Musical passages of complex instrumentation unraveled themselves into musically more understandable sections, as if I was at the live performance. This was revelatory. The spatial aspects in all recordings were more clearly evident than anything I’ve ever experienced in my system.

The cliché most often used to describe improvements in the beneficial effects that equipment can produce is the sweeping away of layers of fog obscuring the view. My analogy would be the change from analogue TV to seeing 1080p Hi Definition for the first time -- a staggering improvement. Images had a sense of realism and solidity with great definition removing layers of artificiality bringing us closer to the real event. This is exactly what the NuForce amps did.

The 9V2 SE’s exhibited a delicacy and nuance that engaged the listener without the edging characteristics that hyper detailed solid state can have. Images were full bodied and developed. Inner detail further revealed previously hidden textures that added realism to the listening experience.

When it comes to musical timbres, words like neutrality and accuracy come to mind. These words are often associated with coldness or sterility which would place the 9V2 SE on the opposite side of “musical”. Here is where these amps truly shine. There is nothing cold or analytical here. The presentation is closer to reality than any amp I’ve had and for me and for me that defines, “musical”.

Dynamics and delicacy don’t often go hand in hand, but with these amps, no problem. First there is the speed and explosiveness these amps exhibit. The music often calls for dramatic and explosive impact as in Pictures at an Exhibition. The ability to start and stop and respond with instant energy is wonderfully evident with these amps. At the same time, during the quiet passages, delicacy and refinement manifested itself in many ways. Listening to flutes and triangle strikes floating effortlessly in space was tactile. Those subtle sounds that orchestral members make while performing were evident. Those creaking sounds, chair movements, page turnings, breath intakes were all there in an organic lifelike way that added to the music’s performance.

Power Cords

Up to this point, there seemed to be only one weakness that I could perceive -- a reticence in the area of bass performance as compared to the Innersound amps. The bass was tuneful, with superior inner detail and texture and equal extension, but lacked the fullness and slam that I’d grown used to with the Innersound amps. As I indicated in the opening of the review, I was using the supplied power cords to make my evaluation of the NuForce amps, but I was using my reference, Acoustic Zen’s Absolute power cord on the Innersound amps. Read my August 29, 2005 review for a full description of the Absolute power cord’s characteristics. It was time to move my reference power cords onto the NuForce and see what effect they would have. After all, we know that power cords can have a major effect on equipment performance, and when one is evaluating equipment performance, it’s imperative to minimize the number of variables to understand their contribution. Using the same power cords would reflect that approach.

My immediate impression was one of awe. The NuForce amps went from excellent to ‘absolute reference’ quality (pun intended). Any reservations I had about these amps completely disappeared. The bass response was now more full bodied and had the slam I had grown used to with an increase of inner detail. Images, in general, were even more three dimensional and dynamics were improved as well. All of the prior observations I had made about these amps were augmented by these power cords. Spatial cues, inner detail, vocal textures, and I could go on and on. Suffice it to say these power cords with these amps were magical. If only I could afford more of those Absolutes. Now, spending the same amount for power cords as your amplifiers seems crazy insane but say what you will, it’s all about the sound. The Innersound stereo amp started at $5k and increased to $6k. The NuForces are $5k for a pair of monoblocks, so amp costs are comparable. The problem is I need four power cords, not two. There’s the rub. I’ll be searching for cheaper alternatives, though I fear it will be well nigh impossible.


NuForce has to be congratulated for achieving reference quality amplification that can compete with the ‘mega monsters’ out there at a far more real world price. Add the Acoustic Zen Absolute power cords, or equivalent, and you have amplification that places you in rarified air. If one is going for state of the art amplification and we’re talking $20k a pair and higher, you still need high quality power cords to achieve the best result. In comparison, the NuForce 9V2-SE is a downright steal. You’ll save a fortune so you can afford those power cords and a Caribbean vacation with the wife and kids. too.

About half way through the review I received a new SACD/CD player, the Marantz SA-7S1. I don’t want to give away too much now, but the better your sources and ancillary equipment you throw at these amps the more they shine. As such, the NuForce amps will take place of pride in my system and become my new reference amplifiers. Thank you, Jason Lim.

[It is with great pleasure that we award The Audiophilia Star Component Award to theNuForce Reference 9 V2 Special Edition Monoblock Power Amplifiers. Congratulations! - Ed]

p.s. I’m hearing from my colleague, Henry Wilkenson, who’s reviewing their preamp, some very interesting comments. Stay tuned.

Musical Choices

Reference Recordings RR-96CD Rachmaninoff: Symphonic Dances Oue/Minnesota Orchestra
Pablo OJCCD-744-2 Clark Terry/Freddie Hubbard/Dizzy Gillespie/Oscar Peterson: The Alternate Blues
Telarc CD-83373 Ray Brown: Some of My Best Friends…The Piano Players
Capital 72434 94756 2 5 Frank Sinatra: Sinatra Sing for Only the Lonely
Telarc SACD-60042Moussorgsky: Pictures at an Exhibition-Maazel/The Cleveland Orchestra
Telarc SACD-60575 ORFF: Carmina Burana-Runnicles/Atlanta Symphony Orchestra and Chorus

Associated Equipment

Amplifiers: A pair of Innersound iPower 330’s, 4-NuForce 9V2 SE’s monoblocks
Processor: DEQX PDC-2.6P
Preamplifier: Innersound iControl
CD source: Classe CDP 100
Analogue source: Avid Volvere / RB300 arm.
Cartridge: Shelter 7000
Speaker cables: Acoustic Zen’s Absolute, Wasatch’s Ultama
Power Cords, Acoustic Zen’s Absolute and Gargantua
Interconnects: Acoustic Zen’s Absolute
Accessories: Sound Fusion’s Sound Boosters, Black Diamond Racing Cones, Soundcare products, Vibrapods, Acme Audio Labs wall outlets. Black Noise 2500 and Eight power conditioners.

Manufactured by NuForce, Inc.

356 South Abbott Ave
Milpitas, CA 95035

Primary Phone: +1-408-627-7859
Secondary Phone: 1-408-262-6777
Fax: 1-408-262-6877
Skype Id: nuforce-sales

Price: US$5000.00 (pair)

Source of review sample: Manufacturer loan


NuForce website