Brian Kahn is the longest tenured writer on staff at HomeTheaterReview.com. His specialties include everything from speakers to whole-home audio systems to high-end audiophile and home theater gear, as well as room acoustics. By day, Brian is a partner at a West Los Angeles law firm.
quickly become a major player in the audiophile grade, Class D
amplification market over the past five years. While the NuForce
product line is now quite extensive, ranging from amplifiers to
headphones, the company is best known for their Class D mono block
amplifiers, the latest version of which is the Reference 9 V3 Special
Edition reviewed here. The NuForce amplifiers differ from traditional
amplifiers in that they are a "switching amplifier" or "switched power
supply amplifier." Most switching amplifiers on the market today are
digital switching amplifiers that are considered by most to be a Class
D design. The NuForce amplifiers distinguish
themselves from this group of amplifiers by utilizing a closed-loop
system with analog modulation driven by the audio signal. A traditional
analog amplifier is controlled by fixed frequency, carrier based pulse
width modulation. The NuForce topology is said to greatly increase
efficiency, bandwidth, control (damping), phase problems, linearity and
signal to noise ratios.
"Hallelujah" from Jeff Buckley's Live at Sin-e (Sony) is a well recorded piece that I have listened to on many systems including in my house with the V2 version of the NuForce amplifiers. The overall sonic character of the V3 amplifier is very similar to the prior V2 amplifier, with some small but noticeable improvements. The V2 Special Edition that I had previously reviewed was already an excellent amplifier, but like any other component there is always room for improvement. As before, the amplifier was fast and detailed while maintaining tonal accuracy. I recall thinking that the prior V2 version as having similar sonic characteristics to Halcro's pricey MC amplifier series but slightly less refined. The V3 is noticeably more refined and would give the Halcro a run for the money in that regard. What does that mean to the listener? On this track I found the Jeff Buckley's voice and guitar to be slightly more palpable and three dimensional than before and with a greater sense of presence. Through both the MartinLogan's and the Acoustic Zen's I noticed a deep soundstage. The high end was even more improved than the midrange. My listening notes indicated that the V2 Special Edition could be slightly forward in the higher regions; the new V3 was more extended and sweeter, and I never had the sense that even with the Adagio's ribbon tweeter that the amplifiers upper limit had been reached.
An album I have been listening to lately is the all-time classic, Dire Straits' Brothers in Arms (Warner Brothers). I have this album stored as a full resolution FLAC file and access it via my Logitech Transporter. I went in and sat down for a closer listen, selecting the track "Money for Nothing." I immediately noticed that even at higher volumes the higher frequencies remained strong and open, becoming ever so slightly harsh only at insanely loud levels. Most wouldn't push these amps to this level of output but I wanted to see just how far I could take it and my ears seemingly gave out before the amps did. There's lots of power coming from these relatively small amps.
On the other end of the audio spectrum, I listened to a couple of albums I have been using lately to test the lower end: The Black Eyed Peas' latest album, The E.N.D. (Interscope) and the ubiquitous It Happened One night by Holly Cole (Blue Note Records) . The synthesized bass line in "Boom Boom Pow" was sharp. I was particularly impressed by the NuForce's control over the Adagio's woofers as there was absolutely no smearing of the bass notes. The bass notes appeared to have more weight than with the prior V2 version but still were a bit shy of the bass powerhouses such as the Krell FTB series of amplifiers. The acoustic bass on Holly Cole's "Train Song" from her album It Happened One Night (Blue Note Records) is an often used demo as it provides some reasonably detailed, well recorded and reasonably deep bass notes. The NuForce amplifier's speed and clarity were great assets here. The leading edges of the notes were sharp, and the decay was naturally extended. The NuForce also did quite well with female vocals. Holly Cole's voice seemed to come from a spot a just behind the plane of my speakers with a good sense of air and space.
Throughout my listening sessions the constant factor with the NuForce was a sense of quickness. The amplifiers always seemed to be quick to respond to any change in the input signal. After the amplifiers were fully broken in they also leaned slightly towards the warm side yet they were very revealing; on some systems they may be too revealing of system shortcomings. When listening to CD's I often felt like the amplifiers were lacking the ultimate level of refinement I have heard in the absolute best of amplifiers. However, this already narrow gap in refinement levels was dramatically narrowed when I listened to some 24 bit FLAC files. I joined the Bowers & Wilkins Society of Sound. I downloaded Peter Gabriel's newest album, Scratch My Back. Gabriel's vocals had a sense of presence and realism that I had not heard with any of the CDs I listened to. The violins on the track "Listening Wind" were particularly lush and vibrant. With both the instruments and vocals there was a significantly greater sense of presence.
My impression is that slower amplifiers may hide the lower resolution sources by a very slight smearing of details which may sound similar to, but not the same as, the sonic qualities often described as "liquid" or "organic". The NuForce amplifiers are true to the recording, whether or not this means they are true to the music will depend on the quality of the recording, perhaps more so than with other gear, as the inadequacies of the recording are likely to be revealed by the speed and detail of these amplifiers.
The NuForce Reference 9 V3 Special Edition speakers can be ruthlessly revealing and will require careful system integration. The slight reduction in power between the V2 and V3 series may cause problems if your preamplifier is passive or low gain. Likewise, inefficient speakers may also not be suited to these amplifiers if concert level volumes are demanded. Another speaker compatibility issue may arise if you have partially active speakers. In the past I have had speakers whose powered sections were not activated by a Class D amplifier.
Sonically, the amplifiers perform extremely well and are among the best sounding amplifiers I have had in my system including class-A, class-AB and class-D. However, they are not 100 percent neutral and consistent throughout the frequency range. The variation is slight but I found their sonic character to gain warmth as you move from the lowest to highest frequencies. Personally, I found this slight deviation from absolute neutrality to work well as I liked my lows to be cool and controlled and my highs to be warm and extended.
The NuForce Reference 9 V3 Special Edition improves upon the already excellent NuForce Reference 9 V2 Special Edition amplifiers which I purchased over a year ago. The difference between the V2 and V3 is evolutionary rather than revolutionary. The differences were not huge but they were noticeable and appreciated as they addressed some of the items that came to mind when I listened to the V2's and wondered, "This is good but wouldn't it be great if they could also...." The biggest improvements came at each end of the frequency range with more controlled bass on the one end and warmer, more extended highs on the other.
The reduced gain allowed my preamplifiers to work in their optimum volume range; however the reduced gain may prove incompatible with low gain or passive preamplifiers or with inefficient speakers. Thankfully NuForce offers an in-home audition program so you can try the amplifiers out on your own system. If you are looking for an amplifier that will give you a lush and smooth midrange that will hide the imperfections in the recording or your system, look elsewhere. The NuForce Reference V3 Special Edition amplifiers will let you see deep into your music, bringing out more of the information that would otherwise be buried by less detailed products. The Reference 9 V3 Special Editions, being a touch on the warm side, let speed and detail shine without the analytical sterility normally associated with these characters. All in all, the NuForce Reference V3 Special Edition won't sugarcoat a bad recording but they will coax a ton of enjoyable musical detail out of high quality recordings and if you have high resolution recordings, this amplifier will let their increased resolution really shine through.