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Positive Feedback ISSUE 33
september/october 2007



Reference 9V2 (Version 2) SE amplifier upgrade

as reviewed by Robert H. Levi







Avalon Eidolon and REL Stadium III subwoofer.

E.A.R. 324 phono preamplifier, E.A.R. 890 amplifiers (ran as monos), NuForce Reference 9 SE V2 amplifiers, E.A.R. 912 preamplifier, and an E.A.R. 834L Tube Line Stage.

VPI Scout/JMW 9 tonearm, VPI SDS Controller, ZYX R-1000 Airy 3-XSB phono cartridge, E.A.R. Acute CD player, ModWright Sony 9100 Player with tube power supply, ModWright Sony 9100ES with Signature Truth Modifications, Mod/Bybee Filters and Revelation Cryo Silver Umbilical. Alesis Masterlink 24/96 Recorder/Playback Deck, and the Benchmark DAC 1 revised. Grado Statement Phono Cartridge. Pioneer DVL 919 LD/DVD Player, and a Marantz DV8400 DVD/SACD/CD player. Magnum Dynalab MD-108 Reference Tuner, Marantz 10B FM Tuner, Day Sequerra Reference FM1 Tuner, and Scott 350B FM Stereo Tuner, AQ 7500 FM Antenna, Stax 7t Electrostatic headphones, Grado Reference 1 headphones, and a Grado headphone amplifier.

Kubala-Sosna Emotion, Harmonic Technology CyberLight, Harmonic Technology Magic 2, Dual-Connect interconnects, Dynamic Design THB Nebula, Soundstring, Kimber Select balanced, Kimber TAK phono AG, Kimber Hero balanced and single ended interconnects, and Acoustic Zen Silver Reference II balanced interconnects. Kimber D-60 Digital Interconnects. Kimber Select 3038 Silver, Kubala-Sosna Emotion, and Harmonic Technology Magic Reference Silver speaker cables. Kimber Palladian, Tara RSC and Decade, Tice, Soundstring, and Kubala-Sosna Emotion AC power cords.

Monster Reference 350 Mark II v2 Power Conditioner, World Power Power Wing, Tice Clock, and Audio Prism Quiet Line IIs. Cable Cooker 2.5, Winds Stylus Pressure Gage, Bedini Ultra Clarifier, VPI Record Cleaning Machine 16.5. Audio Magic's Quantum Physics Noise Disrupters.


I have been testing and auditioning the NuForce Reference 9 series of amps as soon as they hit the market. The very latest and most sophisticated to date is the NuForce Reference 9V2SE Monoblock which is one of the most harmonious solid state or digital amplifiers to ever entertain these ears via my number one reference system. With more textural nuance than a Halcro or Boulder, more suavely persuasive presentation than even Theta, and with comparable dynamic range to a Pass X350.5, this is one of the best solid state amps I've heard to date. I don't care if it's digital or class xyz, the proof is in the listening.

I checked the NuForce web site for details about their unique amplifier operating system. Here's the gist:

"NuForce™ amplifier technology is based upon the principle that a power oscillator can be modulated by an audio signal so that it produces an amplified audio signal obtained with a reconstruction filter, without the bandwidth limitation of a fixed frequency carrier-based conventional PWM control. It uses a high-performance analog modulation technique and a close-loop control system. Therefore NuForce refers to its audio amplifier as Analog Switching Amplifier."

It's also quieter than a musical mouse, devoid of any FM Tuner interference, provides nearly unmatched depth perspective and imaging, and is involving to listen to over the long haul. The 9V2SE is one of the most relaxed and effortless sounding solid state amps on the market. At $5000 for the pair, it's also the most expensive NuForce amp to date, but its chump change compared to what you get for your money.

The 9V2SE is fully balanced with premium connectors. It may be run single ended or balanced for identical results. I used the extraordinary and harmonious Kubala-Sosna Emotion Interconnects and AC cables for superb results. The cables were more expensive than the amps, but the NuForce monoblocks merit such an investment. With revealing and hard to drive Avalon Eidolons, I was mightily impressed. Their 300 watts into 4 ohms and super low measured distortion combined to reveal lovely music no matter what top quality source I employed. Dynamics were to die for and the micro dynamics were as entertaining as the macro dynamics.

The 9V2SE Compared to the 9V2

The 9V2SE version is faster and snappier than the 9V2. I noticed improved imaging as well. I heard new tightening and texturing in the bass. Imaging was more, actually much more realistic. Now loaded with top high speed capacitors and premium parts, all my music sounded more like, well, music. The 9V2SE goes from the excellent solid-state 9V2 piece (which requires about $8000 relatively speaking to equal it musically); to a solid-state piece you'd need to spend five figure dough to equal. The V2SE reminds me of the excellent McIntosh 502 or 401 in numerous ways. I'll say this. The NuForce Reference 9V2SE is the best digital amp on the market today. It can be compared to the best solid-state amps out there and not be embarrassed. This is one of the rare solid-state amps I might call "luscious." You see why I'm so impressed.

I also am aware of a lower, almost vanishing grain. I hear more air and ambience than in any previous version. A subwoofer might also be a thing of the past with this amp - the bass is that terrific. What a bargain! Plus, both monoblocks can still be carried with one hand!

Another big improvement involves electrical interference. It's gone! So are any clicks or pops or hiss or anything which might identify the 9V2SEs as digital. I tried to blow them up, clip them, suddenly turn them on or off, or over heat them. Nothing happened. They still sound and work great. By the way, they require 70-80 hours of music run in for best performance and never turn them off.

Here's the big one. Definition. It's just spectacular. The smallest, finest details pop with an energy that is maximally delightful and entertaining. With no etch and just the tiniest amount of coolness, we're talking see through sound. The Avalons disappeared as often as they do when I used my superior E.A.R. 890 Tube Amps. In fact, it will take top tube amps to show you the few shortcomings of the NuForce monoblocks. Don't have tube amps? Don't worry, you'll be too busy trying every great reference disk and LP you own to see what new info might be revealed. Plus, instruments and voices sound realistic with very accurate tonal colors and enormous layering. These amps are extraordinarily truthful and tuneful and a testament to a company that's done their R&D. Based on added definition and texturing, I'd buy the 9V2SE over the 9V2. It's $1500 very well spent!

With the ModWright Sony 9100—with the tube power supply—the 9V2SE is startlingly powerful and stunningly musical. This is a marriage made in audiophile heaven. With the E.A.R. Acute, you'll think you are listening to vinyl! The textures are magical. Your front-end will become more important with an amplifier this revealing! From a high value perspective, only the top McCormick designs come to mind by giving you this kind of bang for the buck. Though the NuForce 9V2SE has more textural nuance and power than the McCormack gear …you'll have to look at McIntosh or Krell for superior sonics with their best pieces and much higher costs and weight. These little NuForce amps sound like they weight 100 lbs.!


No mechanical or ergonomic problems here. The amps seem to very slightly emphasize tape hiss when it's present on a classic recording. I find this consistent with solid-state amps in general. The good news is that its very soft hiss, like a cloud—which is the right sound. I'd also like even more warmth, but you'll need to buy tubes for that. The NuForce's are about as good as any solid state gets warmth wise, a significant achievement and advance for this design.

In Conclusion

The NuForce 9 has evolved into the NuForce Reference 9V2SE and its performance has continued to improve. No baby steps for NuForce. Each incarnation has been a sonic leap frog and the latest is no exception. Good news is NuForce will update your amp anytime you want. My original 9 went to a SE then to a 9V2SE …no worries. All the digital quirks have vanished including tuner interference and sonic pops. And the sound is now magnificent and worth its weight in gold coin. It would take a solid state amp costing substantially over $10,000 to equal the definition and musical verisimilitude of the 9V2SEs. They reveal trend setting definition and imaging compared to any solid state amps. Only top tube amps will surpass these powerful, but diminutive monoblocks or mega buck solid state gear. They are relaxed and pleasing to those listeners most sensitive to solid state reproduction of which I'm one. Use with the best cables and ancillaries you can afford and forget about their lowish price tag. My ruthlessly revealing Avalons were oh so happy with them. The NuForce Reference 9V2SEs have become my solid state reference against which all new solid state amps will be judged. Well done NuForce. Most highly recommended. Robert H. Levi

9V2SE amplifiers
Retail: $5000 a pair

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