The NuForces offer lively and expressive dynamics, doing an especially good job with leading edge transients and moderate to large orchestral swells. One potential problem, though, is that the amps are so expressive that you tend to forget that they produce “only” 160Wpc; when pushed to their limits the Ref 9s eventually run out of steam before blockbusters such as Musical Fidelity’s kW500 would. When driven at less than “go-nuts” volume levels, however, the NuForces paradoxically sound more authoritative and dynamically alive than many higher-powered amps do.
Finally, I found the Ref 9s produced very wide and deep soundstages, though not quite on a par with the MBL 9011s or, especially, the ASR Emitter II (the ASR is, I think, in a class by itself in terms of soundstage depth and precision). Nevertheless, the NuForces can go toe-to-toe with amps several times their price and prevail by virtue of their uncanny ability to delineate layers of front-to-back depth in the soundstage, and to reproduce small reverberant details that suggest the acoustics of the recording venue.
What can’t the Reference 9s do? Well, one thing they don’t do, or at least don’t do easily, is to present the sort of holographic, “glowing from within” midrange qualities that the very finest tube amplifiers sometimes exhibit (the VTL Siegfrieds and certain WAVAC amplifiers would be good examples). Though I would never call the NuForces sterilesounding, they do have a certain accurate- to-a-fault, garbage-in/garbage-out quality. Basically, these amps will try and make speakers conform to the incoming music signals, for better or worse. But in a sense this very faithfulness to the signal is what makes the Reference 9 so rewarding on great recordings.
An open-ended question, and one that will bear further research, is whether other modern Class D amplifiers sound as good as the NuForces do. Thus far, I’ve briefly heard Class D amplifiers from Channel Islands Audio, Kharma, and Red Dragon Audio, and felt that each offered a lot of potential (though each sounded different from the others). I feel safe asserting that Class D technology has come of age, even for demanding audiophiles.
Prospective buyers should know that the NuForce amps have some minor quirks, which, to NuForce’s great credit, are mostly covered in the amps’ documentation. First, the amplifiers require about 75 hours of burn-in before sounding their best. Second, the amps must be connected to loudspeaker loads before being turned on. Third, the amps produce an annoying “scrritttch” when first powered up. Fourth, the NuForces sometimes exhibit a small but audible increase in background noise when preamp outputs are temporarily muted, though when preamp outputs are not muted the NuForces become dead quiet. Finally, the Ref 9s are very sensitive to ancillary cabling, input connectors, binding posts, and the like. For this reason I strongly recommend ordering your Reference 9s with the optional WBT NextGen RCA jacks (these will set you back an extra 55 bucks per amp, but they are worth every red cent).
Do you find it hard to swallow the idea that a $2610 pair of monoblocks can compete on a nearly equal footing with amplifiers many times their price? I certainly did, but after loaning the NuForces to a colleague whose reference system is far more exotic than my own, the verdict stayed the same: The Reference 9s really are that good. Therefore, I urge you to run, not walk, to the nearest NuForce dealer to audition a set ASAP. If your reactions are even half as favorable as mine, you’ll need your checkbook. Go, now.