NuForce Reference 9 Monoblock Power Amplifier

The best affordable amp on the planet?

Several months ago I visited three members of The Absolute Sound team—Harry Pearson (founder and chairman of the Editorial Board), Jonathan Valin (associate editor), and Atul Kanagat (advisor to the “Cutting Edge” section) and had the opportunity to audition their superb reference audio systems. Many things stuck with me about those rich listening experiences, and one was the vivid memory of how excellent the respective system amplifiers were. At the time, Pearson’s system was powered by an ASR Emitter II amp, Valin’s by a pair of MBL 9011 monoblocks, and Kanagat’s by a pair of VTL Siegfried monoblocks. Then and now, I felt those three were among the finest amplifiers on the planet, but my enthusiasm was tempered by the sobering realization that each cost more than the car I drive; I could no more buy one of those amps than I could a fleet of Lear jets. Sighing, I made the rational choice to accept some cost-driven tradeoffs in my reference electronics, a decision that served me well right up until a pair of downright amazing and affordably priced giant-killer amplifiers came along and changed everything. Enter the NuForce Reference 9 monoblocks. Within a few hours of installing them in my system, I felt certain new benchmarks in affordable excellence had arrived.

NuForce’s Reference 9s are small, attractively (but not extravagantly) finished, 160 watt, Class D monoblocks priced from $1250 to $1305 each. The Reference 9s are equipped with switch selectable balanced and single-ended inputs (though users should run cabling to one input or the other, but not both at the same time). When I used the “Class D” descriptor some of you probably thought, “Oh, so the NuForces are digital amps,” but in fact they’re not. NuForce VP Casey Ng stresses that the Reference 9s are “analog switching amplifiers,” and the distinction involves more than mere semantics. In practice, the NuForces differ from many other Class D amplifiers in three important respects: First, they offer very wide bandwidth (20-50kHz); second, they can drive low impedance loads (350 watts @ 2 ohms); and third, they are based on proprietary circuit topologies developed by NuForce—not on any of the popular off-the-shelf Class D amp modules such as those offered by Tripath, Bang & Olufsen/ICEPower or Philips/Hypex UCD. Interestingly, the NuForce amps were designed by the company’s chief technology officer—an engineer named Tranh Nguyen, whose design accomplishments include development of the power system for the Tomahawk missile and who holds several patents relevant to Class D amplification. But enough technical background; let’s get to the heart of the matter. How do these amps sound?

Frankly, the NuForce Reference 9s do so many things right that I hardly know where to start, but let’s begin with the two qualities that grip most listeners first: resolution and transparency. The Ref 9s offer a truly extraordinary level of see-through transparency, and as an audiophile friend so aptly put it, “Their transparency is real, not a fake artifact caused by brightness.” That brings me to a second revelation: These little amplifiers not only deliver gobs of musically relevant detail, but do so without imposing the fingernails-on-a-chalkboard torture of excess brightness. In this respect, the Reference 9s combine some of the whole-cloth sonic integrity of the mighty MBL 9011s as well as a good bit of the focusgoes- on-forever clarity of the ASR Emitter II. How does this play out in musical terms? Well, for me it means falling in love with the timbres of individual instruments and voices all over again. As I write this, for example, I’m listening to the Quartetto Italiano perform the Dvorzak “American” String Quartet in F Major, Op. 96 [Philips, LP] savoring the way the NuForces reveal the profoundly complex voices of each individual instrument, as well as the interplay of those voices as they meld to form a greater whole (and isn’t that the real magic of great string quartets?). Similarly, on good live recordings, such as Eva Cassidy’s Live at Blues Alley [Blix Street Records], the NuForce’s bring my system alive with the sort of crackling, electric intensity you typically experience only in live music venues—an intensity heightened by the amplifier’s ability to capture, simultaneously, the delicacy of Cassidy’s voice, the scorching heat of electric guitar solos, and the giant-hearted punch of the electric bass. The word picture I’m hoping to paint, here, is one of an amplifier that essentially never sounds congested, regardless of the complexity of the material being played (a quality the the ASR exhibits to an even greater degree).

Next, as a bassist, I feel compelled to point out that the NuForces deliver the best doggone bass-pitch definition and control I’ve ever heard from any amplifier. Part of what’s going on is that the NuForces offer a damping factor greater than 4000 (no, that’s not a typo), so that when the Ref 9s tell woofers what to do, the drivers have little choice but to shut up and follow orders—precisely. The sonic results can be eyepopping in several ways. First, the Ref 9s seem to give some speakers (e.g., my Magnepans) about an extra half octave of bass extension they never had before. Second, the amps draw out layer upon layer of bass textures and detail you may never have heard before. A few nights back I put on master acoustic bassist Dave Holland’s Emerald Tears [ECM, LP] and listened in shocked amazement as the NuForces revealed one new subtlety after another (the intricacy of Holland’s solo work is just unbelievable!). The only word of caution I would offer is that the NuForces handle low frequencies with the utmost control, and therefore will not artificially “warm up” either recordings or loudspeakers that lack bass. But put these amps together with recordings and associated gear that can do bass well and it’s “fasten your seatbelts” time.