Nuforce P-8S Preamp and 8.5V2 Power Amp


  • 4 x RCA inputs.
  • 1 x RCA, 1 x unbalanced XLR outs
  • 12V DC Tigger Out.
  • Digitally-controlled switched attenuator. Volume Range: +30dB to –70dB with 0.5dB steps
  • Dynamic Range: > 100dB
  • Input Impedance: 4K ohm
  • Output Impedance: 40 ohm
  • THD+N at 1kHz: < 0.01%, typically 0.003-0.005% S/N Ratio > 85dB
  • Frequency Response at 20-20kHz = +0dB/-0.2dB at 20-170kHz = +0db/-3dB Maximum output = 8V RMS
  • Dimensions: 1.75”H x 8.5”W x 16”D Weight: 6 lbs. Power Requirements: 90-240VAC, auto select.
  • Stereo 8.5 V2 Per Channel
  • Watts Per Channel: 160w @ 8ohms, 200 @ 4ohms, 200 @ 2 ohms
  • Power bandwidth: 100 to 20 kHz +/- 0.8 db 10 Hz -0.5 db 60 kHz -3 db
  • THD+N = 0.03%, 1kHz, 10W
  • Input impedance: 45K ohm
  • Gain: 27 db
  • SNR = 100 db at 100W
  • Dimension: 8.5″ x 14″ x 1.8″ (height does not include feet)
  • Worldwide AC voltage (84VAC to 264VAC). No need for AC regulator if the AC voltage falls within the specified range.
  • Weight: 9 lb

Can you (almost) have it all for so little?

Let me get to the point. These small, light, pick-em-up-in-one-hand boxes are so good that you cannot help but wonder if the world is mad. Here we have modern design in a partner-friendly package that won’t break the bank to own, which sound really good and yet people who have never heard them will dismiss any claims on Nuforce’s behalf as hype. I don’t pretend to understand how Nuforce’s desigers have done it but they’ve done it. These products are good…I mean really good. Ok, now calm down, park your prejudices and take my advice if you are about to spend money on amplification, go listen to these to learn what’s available at this price.

By now, you’ve surely heard all about Nuforce designs, even if you’ve never heard them for yourself. Half-sized, reasonably priced, slick designs, the amps have attracted a rabid following and strong critical support in many major publications, counter-balanced by some negative reviews from traditionalists who feel only tubes will do, or from cynics who just can’t imagine that a class D mini amp could compete with large box Class A or A/B designs. Aware of the (mis)perception, Nuforce even offers home trials for $1 through participating dealers and I suspect that many people who try end up keeping them. To give you some basis for my impressions, I’ve heard Wyred4Sound, Spectron and now Nuforce amps, all in my own reference system and all for far longer than a casual listen. I’ve lived with each for several months, trying them with various preamps and cables, so I feel I’ve got a handle on various class D implementations and it’s clear to me that Nuforce has got the quality for the dollar equation down better than almost anyone else.

Nuforce P-8S Preamp and 8.5V2 Power Amp

Nuforce’s product designs have received several patents and claim green technology status for their energy efficiency. Designed in the US and manufactured in China and Taiwan, the process involves, according to company spokesman Jason, routine listening tests with audiophiles who provide the kind of audience the company aims to serve. The range now includes the ultra-affordable Icon amp ($250) and the top of the range 9.5SE monos for upward of $5k the pair. The present coupling can be had for a 10% discount if purchased together, bringing them in at $3510 the pair, for which you get the heart of a very good audiophile system that just needs speakers and a source to make great music in your home. You can find detailed descriptions and specifications at, which I won’t repeat here, my job is to review the sound, but a peek inside gives you some idea of careful layout and use of awardspace involved.

The two components arrived in the same box, light enough to make me wonder if I was missing something, but upon opening I was reassured with two separate slim packages, each containing a velvet liner-covered silver component. I mention the size and weight a lot in this review because it really is quite surprising how Nuforce has delivered so much in such a small design. While they are both 16″ in depth, their front elevation is a disappearing 1.75″ x 8.5″, making my half-sized PS Audio GCP phono stage look bulky in comparison. The preamp weighs 6lbs, and comes with both balanced and single ended outputs, but only single-ended inputs (4 pairs). A 12V Trigger Out allows P-8S to connect to the 9lb Stereo 8.5V2 for turning the power amp on or off, a boon if, like me, you keep forgetting the correct order for turning components on and off and you wish to avoid noisy spikes. The look of these components is slim, modern, silver, with blue LEDs that shine brightly (the amps are also available in black). There are no toggle switches or rear settings to worry about, control is via two pleasantly sized volume and input selector knobs, a straightforward plug and play design. The preamp comes, however, with the most original remote control, a hexagon shaped, futuristic black metal wand which controls volume and input selection simply (useful since the preamps volume knob requires more turning to increase the volume than I’ve ever experienced, though it remembers settings if you don’t toggle the power switch at the back). Its weight alone suggests serious thought, unlike most plastic throwaways that come with audio components.

I allowed for break-in with the pre and power combo as a unit powering a pair of Kef 103/2s in my second system, and playing around with the Audio Horizons Tube Buffer feeding the pre or sitting between pre and power (see review of the buffer in the March 2009 issue). As I noted previously, the Nuforces really made the Kefs dance, offering robust musicality and plenty of detail, but perhaps being a little hard in the lower regions, or at least in the depths offered by the Kefs. I ended up really liking this set up when I employed the buffer too but much of the quality of sound is limited by the Kefs which always seem flat but a little uninviting, and the tube buffer helped to give some roundness to the sonic presentation. While this is not my reference rig, I confess I was mighty impressed already. The marriage of the ultra modern looking Nuforces with my 25 year old Kefs (which have followed me around the globe and carry the scars to prove it) made for an odd sight but a truly impressive bedroom or small room system. I was now ready for the main rig.

Putting a sub $4k pre/power combo to work on a $20k plus pair of speakers might seem like a futile exercise but I don’t share this view. To my ears, a component has to earn it’s price tag and I’ve never been one to believe there was a strong correlation between cost and sound in amplification. No, I don’t feel all amps are the same; to my ears they are definitely not, but since I had such a great experience with the $3600 Audio Space Ref 3.1 integrated tube amp last year driving my Vons, I believe high priced amps really have to show their chops if they are to justify their price. With the Nuforce amps now available at lower price points, other manufacturers better watch out, value is getting a new name.

I connected everything up with PS Audio Transcendent cables, using both Virtual Dynamic David (almost big enough to lift the the little power amp off the rack!) and new VSA Biwires to feed the speakers, with everything plugged into my PS Audio PPP line regenerator which handily serves as a master on-off for the entire system. Like the rest of my gear, the Nuforce pair sat on a Steve Blinn Acedo rack with 1″ thick maple shelves. While I played around with the tube buffer for its review, I only seriously began reviewing the Nuforces when they had sole control of the set-up and remained in there for over two months, with occasional swap outs for comparisons with my reference amps.

Little box, BIG sound

If ever there was a case for the importance of blind testing, component size effects must be one of the obvious demonstrations. Big heavy amps exude power, you expect them to take control and stamp their authority on your woofers. The Nuforce power amp just looks too damn small to be able to work with large speakers but hearing is believing. Sure the VR5SE’s are sensitive but the Nuforce 8.5v2 just packs a punch across all frequencies that belies its size. Cue up the usual suspects. Diana Krall’s “All or nothing at all” from Love Scenes (Impulse Records, 1997) opens with an acoustic bass run that should have all notes reproduced evenly, not louder and softer in parts, and the Nuforce pairing passed this test easily. When her vocals join in, you know you either have a system that gives you pleasure or you don’t. Even on ordinary components, most people tell me this album sounds good to them and that’s true enough. But with really good components there’s a greater intimacy to her voice, and the very best components elevate the sonic quality just a few notches higher that usually captures the attention of anyone within listening distance. The Nuforce pair might not provide the very best vocal reproduction of this song that I’ve heard (that awards goes, so far, to the Audio Space 3.1) but they take the sound to a level that is better than most.

Nuforce inside

Pat Metheny’s Day Trip provides a great example of the Nuforce sound. There’s a full, bass undergirding a clean, smooth reproduction that smoothly unfolds before you, with a level of detail in the uppers that is quite surprising. Cymbals tingle and fade in the air in a pleasant, palpable manner that caught my attention but not in a negative manner. Rather, I was taken by how different this little amp sounded in the upper registers to the Wyred4Sound MC4 I reviewed last year which always left me wanting something in this range or could sound hard on transients. Not the Nuforces, they reveal a lively, engaging treble reproduction that partnered very well with my speakers. In this regard, the Nuforce might actually be a bit too lively for some listeners, emphasizing the wash of cymbals a tad but this is really a matter of taste. There seemed more emphasis than I get with the Spectrons or even my older BAT VK500, both of which seem to create a little more space in this region but it’s not as if you can listen to one and say it provides more or less details, they are present with each amp, but the Nuforce combo seemed to put these to the fore a little more. Some critics have pointed to class D as having some kind of “whitish” overlay to the treble, and I am not entirely clear what that means but it might be a reaction to this reproductive balance which is slightly upperleaning.

With chamber music, the combo really created a rich embracing warmth that gave the Emerson Quartet’s Art of the Fugue a mellow texture, inviting you into the music. This actually revealed something of the Nuforce’s chameleon quality, an ability to sound slightly different with various recordings and genres. In contrast to the slightly detailed sound on jazz rock, here the music came out in an almost tube-like manner, with effortless tone and texture. With these amps in my system, it was small group jazz and chamber that really sounded best, not unlike some tube amps I know. With hard rock, the amps have enough punch to convey the drive and rhythm of the music with, again, treble response that is present without ever being etched. The resolving power is not as good as the best amps I’ve heard but unless you hear them side by side, you may not notice, the balancing act pulled off by the Nuforce lets you listen without gear getting in the way.

On orchestral pieces, the Nuforce pairing has few problems. Elgar’s Cello Concerto in Em is a long-term favorite, with Du Pre’s performance consistently drawing me into the music. With this combo the music is smooth, slightly emphasizing the uppers, capturing the sweep of an orchestra’s rise and fall, with a clear delineation between strings, wind and brass, a quality I found attractive. In the opening bars, du Pre’s cello came through with a real presence that placed her more easily apart from the accompanying musicians but in a way that made sense for the music, her cello sonorous and detailed. Other more expensive amps have not quite managed this trick so well.

I’m not too quick to attribute soundstaging qualities to amps, there just seem to be too many other variables in the set-up mix that matter, but without changing speaker locations, I felt the Nuforces were not quite the match of the BAT or Spectron in this regard. They certainly seemed to create a shallower depth on most recordings but I am loath to put too much importance on this as moving the speakers might have corrected this. Since I spent many hours placing my speakers originally, and they are not a simple pair to shift around, I left them in place and noted the results.

I find the Tord Gustavsen Trio’s recordings on ECM to be both wonderful to listen to and a lens on the differences between components of all kinds. The percussive use of cymbals interplaying with acoustic bass and piano over sparse, single note melodies in Being There (ECM Records, 2004) can reveal a lot about how amplifiers affect sound. The Nuforce pairing is quite surprising in this regard, sounding more like a tube amp in its reproduction than some other class D’s I’ve auditioned. This is not to say it matches the rich midrange of the best tube designs but other than a faint hint of hardening at the upper registers that is more noticeably with Gustavsen’s recordings than others, the Nuforce pair offer a smooth and ear-pleasing sonic picture that will engage most listeners.

If forced to characterize Nuforce’s sound, I’d actually describe it as leaning towards the uppers with an almost lush quality, which might surprise those who’ve heard other Class D amps or who’ve read the various forums where such designs are celebrated or dismissed in equal measure. If I have any concerns with these amps it is that they don’t quite have the musical timbre of my references. All music is pleasant and detailed, with a solid reproduction of the full range, and it’s easy to leave them in place to do their thing, they don’t really draw attention. Unlike some critics, I do feel these amps reproduce music that sounds like music but each time I took them out and put the PS Audio preamp with the Spectron or BAT back in, I felt the general quality of my system shifted for the better. But this is in comparison to components costing far, far more. Against such performers then the ultimate resolution of an intrument or voice, and the presentation of space between musical lines is not quite at the same level but you have to listen actively to identify these shortcomings in the Nuforce. The slightly weaker bass reproduction is noticeable mostly by comparison also, I rarely felt I was missing this until I changed amps; if you have such gear already, you’re probably not in the market for this combo but it’s a measure of how good they are that one has to scale such heights to clearly better them.

The Nuforce line is rightly recognized for it’s commitment to upgrading designs that its customers can explore without losing their original investment. I am not clear that this option exists for these designs, though it is conceivable that if the combo is a success then it would make sense to view upgrades to this platform as equally likely. There’s a lively Nuforce forum on Audio Circle where such matters are routinely discussed. I tried to check the preamp driving another amp but the XLR outs did not work on the version I had so I was unable to use it on its own with the Spectrons. I did try the amp alone, fed by my old McCormack TLC-1 preamp in passive mode, both with and without power added. It’s hard to draw firm conclusions from this about the relative strengths of each Nuforce component but I would say the sound did shift as a result of preamp being used, with the TLC-1 adding a more airy resulting presentation in concert with the 8.5V2, perhaps suggesting that the Nuforce P8-S preamp is the major determinant of this combo’s sound. I don’t imagine any one seriously pairing these two intentionally but sometimes odd mixes occur for a variety of real-life reasons. In this case, I’d not worry that the power amp only works with a Nuforce pre, it clearly does not limit itself that much, but the two together do have a particular synergy, both visually and sonically.


It’s not chump change but gaining a complete amplification package for $3500 that offers flexibility, connectibility and enough power to drive almost anything in a sonically pleasing manner is no simple challenge. That this package is so easy to place and move, and, to my eyes at least, looks so elegant, just adds to the attraction. If you have any restrictions on placement or size, you would be crazy to overlook Nuforce, these just deliver a sound that belies their footprint. In complete opposition to the Audio Space Ref 3.1 that I loved so much, there is little room for tweaking here and no maintenance requirement, just plug and play reliability. It sounds different than the Audio Space tube integrated, as you might expect, and the sonic picture you prefer will dictate your preference. Sure the Spectron monos are better to my ears, but at over five times the price one might expect far greater difference between them. The Nuforce amps have a sound that cannot be simply labeled class D, as if that conveys an identifiable sonic signature we all understand. These differ from the Spectrons and both differ from the Wyred4Sound I reviewed last year. Why should we expect otherwise? Over several months I found myself with this pair driving my reference system so well that I actually felt I could live with these. Can I say more than this? So far, this is the best value I’ve heard this year a strong recommendation in affordable audio.

Associated Equipment:

  • Digital: Marantz S-11 S1 SACD player
  • Amplification: Spectron Musician III Mk 2 monos with Bybee upgrade, BAT VK 500, PS Audio GCP 200 with external PS, McCormack TLC1
  • Cables: Virtual Dynamics David speaker cables, Von Schweikert Audio BiWire cables, PS Audio Transcendent XLR and RCA interconnects,

from affordableaudio, By Patrick Dillon