NuForce "Home Series" Quality Compact Audio Gear

Fremont, CA based NuForce has been around for a while. They were traditionally known for their higher-end digital amplification, preamps, and DACs. More recently, they are also well-known for their low priced series of smaller components. When I heard about NuForce launching a new line called "Home Series", I became intrigued—bridging the large gap between models like the $7600 Reference 18 and the $189 Icon seems a wise choice.

Nuforce seems to have their gear divided into three categories, and it can get a little confusing. Catalog links on the left side of this page should help. It shows the "Hi-End" line encompassing preamps, amplifiers (stereo, monoblock, and integrated), and the Reference 9 DAC. I've been calling this stuff the "Reference" line but I now realize that isn't entirely accurate, only a few of them actually use that specific title. In any case, these models are priced in the thousands rather than hundreds, and you'll recognize them right away by their nicely sculptured front panels. Then there's the "Consumer" line which features the "Icon" branded amps and DACs, the uDAC2, the Cube compact speaker, and a few headphones. This line is affordable, with many items being under $200 and its most expensive member being the Icon HDP at $449. So you can see the discrepancy between it and the Hi-End line.

To fill that space, NuForce recently launched the "Home" series. Like the Icon series, the Home products use similar enclosures with minor variation as needed for each individual model. And I personally think they look quite sharp, in a sort of modern, minimalist way—Ikea could use these in their catalog and it wouldn't feel out of place. Pricing tends to be comfortably under $1,000 with the sole exception of the DAC-100 which is $1,095. I reviewed (and enjoyed!) that device at HeadFi not long ago, and frequently used it as a source to evaluate these other Home series models.


DDA-100 Integrated Amp ($549)
Kicking things of for the home series is the DDA-100 ($549) which is an integrated amplifier with a twist. Like every member of the Home series, the DDA-100 (available in black or silver) is 9 inches wide, 8.5 inches deep, and 2 inches high—small enough to fit on all but the most cluttered desktop. Despite the small stature, Nuforce was able to cram a good amount of connectivity into the device. It features dual Toslink inputs, a coaxial input, and of course USB. Astute readers will notice the lack of any type of analog input. That's deliberate—the "twist" I mentioned is the DDA-100 functioning entirely in the digital domain. Also, there just isn't enough room for legacy inputs—I certainly didn't miss them. Also on board is an optical output, meaning the DDA-100 can function as a USB to SPDIF converter, as well as integrating into more complex systems.

So what exactly does a "completely digital" integrated device look like? It's a tricky thing because actual sound, as it travels through the air, is inherently analog. Yet the DDA-100 does not use the typical digital to analog conversion we are familiar with. Instead, digital inputs feed PCM signals straight to the Class D amplification section with no D/A conversion step in between. Class D is also known as PWM or Pulse-Width Modulation. Some people will immediately balk at that description and assume it has no place in an "audiophile" device. Not so fast. Class D amplification spans the range from cheap solutions used to power the crappy speakers in your TV, all the way up to authentically high-end gear like the $5,999 NAD M2 and the similarly priced Bel Canto Ref1000M monoblocks. Assuming all Class D amps perform identically is just plain misguided. It's like making that same assumption about Class A or AB amps—it just isn't true.

The "D" in Class D does not stand for Digital and as amp guru Nelson Pass once said, "PWM is definitely analog". Yes, in simple terms the PWM process involves a binary status for the switch modes of the output devices—1 or 0, on or off—but is actually defined by the duration between switch changes, and as such is practically limitless in intermediate values. That sure sounds analog doesn't it? On the input side, the DDA-100 actually resembles a DAC more than a traditional integrated amp. An AKM digital receiver and NuForce branded USB section accept incoming signals and route them to dual Infineon SAB2403 chips (1 per channel). These are highly integrated devices featuring onboard DSP, sample rate conversion, and digital filtering among other things. Volume control is also handled in the digital domain, accessed from the freely spinning front panel knob or the compact remote. That same multi-function knob pushes to cycle through the 4 inputs (hold it down to go in or out of standby mode), and two pleasingly-dim displays show volume level and active input. The whole thing sounds more complex than it really is—in actual use, the DDA-100 is quite simple and effective.

As far as specs, NuForce rates the device at 50-Watts RMS into 8 ohms and 75-Watts RMS into 4 ohms, with a far higher peak rating. Inputs are limited to 96kHz, a deliberate choice on the USB side to keep things Plug and Play across all platforms. I inquired about potentially improved jitter by using an asynchronous USB interface and NuForce advised that due to their re-clocking process, all inputs measure the same in terms of jitter. So there would be no theoretical benefit to improving the USB implementation in this particular device. The only thing I can really complain about is the sample rate ceiling. I can actually play my 24-bit/176.4kHz Reference Recordings HRx tracks through the coaxial input but it doesn't like 24-bit/192kHz files. And the other two inputs top out at 96kHz as advertised. A minor issue at worst.

My initial task for the DDA-100 was in a desktop system. I used it in a deceptively low key setup to drive the wonderfully transparent Salk WOW1 monitors—just add computer, no messing about with other boxes or interconnect cables. All I needed was a USB cable and speaker cables (obviously). For the latter I used Charleston Cable Company Auric cables because they were so much more flexible and compact than any other cables I had on hand—a desktop system is no place for garden hose audiophile speaker cables. Thankfully the DDA-100 is low profile enough to fit any number of spaces on a desktop. Try that with a full size integrated amp.

My first impression of the DDA-100 was in comparison to the gear formerly occupying that spot—a Resonessence Labs Concero DAC and a Consonance M10S tube integrated. The DAC is an extra variable which simply couldn't be avoided. Nonetheless, the Concero/Consonance setup is a very satisfying pair which I'd say competes well at its ~$1700 price. The DDA-100 had similar levels of transparency and openness, and in fact was surprisingly similar in overall character considering their differences in topology. Keeping in mind the price difference involved, this already speaks highly of the NuForce unit. The DDA-100 exhibited none of the bright, edgy, thin sound that some people erroneously attribute to all Class D amps. What it did have was an unflinching level of clarity—where the Consonance made everything flow smoothly and was relatively forgiving, the DDA-100 had a more direct presentation, for better or worse. Great recordings such as the previously mentioned Reference Recordings HRx tracks sounded palpably real from top to bottom. Even 16-bit/44.1kHz material such as the MFSL edition of Frank Sinatra's Nice 'N' Easy or Kiss Me Hello by Kristin Andreassen sounded exceptionally detailed, with a rich full-bodied tone that I normally associate with larger (and more expensive) separate components. The flip side of this accuracy was mediocre recordings being laid bare. Praise & Blame by Tom Jones and Dancing in the Dark by Tierney Sutton both have significant flaws, and in the DDA-100 system they border on unlistenable. The more forgiving Consonance amp makes them somewhat more palatable, especially with regards to the sibilance in Sutton's voice. Lipstick on a pig? Most definitely. I can see how the DDA-100 would be less appealing depending on one's musical preferences, but given reasonably good material I'd say it really punches above its weight class.

Next I did something which would cause most compact desktop-friendly amplifiers to run for cover—I added the DDA-100 into my 2-channel setup. But this is only fair considering NuForce bills it as a straight integrated amp and never specifically mentions desktop use. The speakers involved were the Sjofn HiFi (the clue) monitors which are 87dB efficient. The room is what I'd call midsized and the usual setup is based around a Parasound Halo A23, which is significantly more powerful than the little DDA-100. The two devices couldn't be more different. The Parasound is a beefy full-sized component weighing in at nearly 30 pounds, packing a linear power supply and a dozen bipolar output transistors. Comparatively, the NuForce looks like a toy. And yet in terms of sound the two are surprisingly close. In fact, the choice of preamp driving the Parasound seems the key factor. Using the AURALiC Taurus ($1799) brings the larger amp up to roughly the same high level of transparency as the DDA-100, albeit with more drive and dynamics, and at a considerably higher price. But using a more affordable device such as the Grant Fidelity TubeDAC-11 ($350) or Matrix M-Stage ($300) as preamp, the DDA-100 takes a clear lead—better transients, more fleshed out midrange, less grain. This tells me the "all digital" approach does indeed reduce bottlenecks. It only makes sense, reducing the number of analog gain stages in an affordable multi-function device seems completely logical to me.

One key strength that the DDA-100 had was the ability to render a believably three-dimensional sound field. This is probably related to the extremely black background and clear-yet-controlled top end detail. Whatever the case, the little NuForce box presented a deep, highly-resolved soundstage that extended well beyond the physical limits of the speaker enclosures. The Taurus/Parasound combo had more authority and could be more convincing with very loud orchestral works, but never quite matched the little NuForce when it came to delicate imaging. Swapping out the AURALiC for my Analog Design Labs Svetlana 2 (a $1500 single-ended triode unit) allowed the Parasound to match and maybe even exceed the spaciousness of the NuForce at the expense of some dynamics. In the end it seems the DDA-100 is a good compromise between the Svetlana and Taurus preamps as heard through the Parasound amp, capturing many (but not all) of their strengths but in a smaller and more affordable package. The caveat would be volume limitations, in a room larger than mine, or with speakers less sensitive than mine, I'd definitely start to worry about maximum volume capabilities, especially with quiet jazz recordings.

This impressive soundstage puzzled me as I recall an early review complaining about a flat, two dimensional presentation. Was it just my particular room or speakers that mated well with the device? Or was something else amiss? Then I noticed the interior of my unit looking very different from pictures posted in that early review. I discussed this with a NuForce engineer and sure enough, my unit is a "V2" model with significant changes. It turns out the V1 power supply was an off-the-shelf design that didn't perform quite up to expectations, despite its impressive looking, confidence inspiring external shielding. The new power supply is custom made for this specific project, using a better topology and improved components. A side effect was the radiation issue being dealt with at the source, meaning shielding was no longer necessary. In addition, the new design had better regulation so the large coupling cap seen in the original was no longer required. These significant changes could explain why I hear things very differently than that initial review.

DDA-100 Conclusion
The DDA-100 is paradoxically versatile and limited. It delivers huge performance from a small enclosure, and can replace multiple larger and more expensive devices in a system with little to no penalty in sound quality. In that sense it is definitely versatile. Yet it's limited in the context of its interactions with the other NuForce Home series models. The only time I see this being an issue is trying to work a headphone into a DDA-100 based system. That limitation, as well as the obvious need to keep expectations in check regarding room size, max volume, and speaker sensitivity, appear to be the only compromises in an otherwise exceptional offering. Whether on my desktop or in my living room, the DDA-100 never failed to impress, and I can confidently recommend it.

Armaegis's picture

Regarding needing more power to drive planar magnetic headphones, I found that their speaker amps did a dandy job of that. Specifically, I have a short writeup of the STA-100 driving my HE-6, comparing vs the smaller Nuforce Icon2 amp and the Centrance Dacmini PX. 


John Grandberg's picture

There's my HeadFi pal now. 

Nice write-up. Since I don't have an HE-6, I didn't even think of using the STA-100 that way. Sounds like it reacts just about the same way as with my speakers. 

Bill B's picture

good reviews, and would be great to also have their UDH-100 reviewed, seems especially applicable for Inner Fidelity users:  24/192 DAC, headphone amp, preamp, in one box.  The price I think around $600?

John Grandberg's picture

...does look interesting. Assuming it has basically the same guts as the DAC-100 but without the fancy case and the legacy inputs, for $450 less (UDH-100 is $649), then it's a great deal. But I can't confirm that to really be the situation or not. 

lithium's picture

Hi John,

great reviews. However I felt perhaps you skimped on the comparisons a bit because of the multi review format. I was interested in the headphone amp/preamp mostly. Also, now that the DAC-100 is discontinued have you had a chance to listen to the DAC-80?

John Grandberg's picture

Yes, I did keep things a bit shorter due to the format. But please ask any questions you might have about comparisons.

The HAP-100 is really quite nice. Tyll still has the similarly priced Lake People G109 that I covered a while back, but from memory the two are very competitive. I'd probably take the G109 for planar headphones due to the much higher current delivery, and I'd stick with the NuForce for HD800 and T1, just based on the fantastic synergy involved.

And yes, I actually did ask for a DAC-80 so I could see if it loses anything from the DAC-100. It just arrived the other day and so far I'm not hearing anything missing. In fact, strange as it may be, the DAC-80 seems somehow better. Not sure why that would be - maybe I'm imagining things. Still need to crack the case open and see what the changes are aside from losing the headphone stage. I'll post my thoughts on the DAC-80 over at HeadFi once I get a handle on it. But so far it seems promising, and saves money when paired with a HAP-100 (no redundant amp). 

lithium's picture

have you had a chance to listen to the soloist SL, the vioelectric V90 or V100? Any other amps in this price range that you got to compare it to?

thanks for all the comparisons as always.

John Grandberg's picture

I haven't heard those Violectric models, but their Lake People counterparts give me an idea: G103 is similar to V90, and G109 is very similar to V100. G103 is not quite in the same league as the HAP-100 so I'm guessing V90 isn't either. V100 seems like the sweet spot. My only potential issue - V200 is "only" $170 more and that seems very tempting. 

Have yet to hear the Soloist SL but I think it has potential since they got rid of that stepped attenuator. I'd guess SL is also better for planars based purely on current delivery. Beyond that I don't know.

I do have the Firestone Audio Bobby in for review. It's a fully balance design, quite nice sounding. MSRP is $799 but I see it available for $599, which is a great price. I'll have a comparison with the HAP-100 in the upcoming review, but for now I'll say it's possibly more neutral, definitely more expansive sounding (especially in balanced mode), but maybe a bit more polite. 

lithium's picture

the G109 is a great value definitely. I was also looking at the audio -gd amps and I have heard mixed opinions about them. There are reports that they cause appreciable coloration. Have you had a chance to try one?

John Grandberg's picture

I've only tried their Reference 7 DAC which I thought was quite good. Everyone tells me the Master series stuff is fantastic so I'll eventually have to give those a listen. 

lithium's picture

Your help is greatly appreciated....

Frank I's picture



I enjoyed the review,\. Well written and had a lot of beef to it. Great stuff!!

emess18's picture

Love my DDA-100!  I am driving it wirelessly from iTunes (Apple Lossless) with an Airport Express through an optical cable.  I have Legacy Audio Victoria LE Monitors (20th Anniversary) which are 94dB efficient.  I originally had a Theta Digital transport/DAC combo, VTL 2.5TL preamp, Pass Aleph 3 amp, and Straightwire Virtuoso cables.  I hardly miss all of that hardware, and I find iTunes so convenient (even for classical music) that I am listening 3 times as much!

Trasselkalle's picture

I've been driving my Mirage M3si (which were well loved when they were new: with the old Rotel RB-991 power amp for quite a few years now. Meanwhile, I've been looking for excuses to get rid of the RB-991 for something more 'serious'. Listening to a large number of power amps - tube to type D - I've thus far failed to find anything I really felt was a clear step up over the RB-991 without going nuts with the money. The RB-991 was an overperformer when it came out after all ( so while it started out as an experiment into solid state (I was a firm tube amp guy until then), 'the itch' says it's time to consider new equipment.

Last year, I threw out my super-nice Copland tube pre-amp (with new and upgraded tubes) for the Nuforce Icon HDP that I had bought to drive my AKG K702. After a long process of denial, I was forced to admit to myself that I liked the much more detailed HDP. As it stands now, I need the HDP for my headphones in the library of our new house and I'm considering what to use as source in the living room with my M3si. I could just go with another HDP, but I'm not going to sit there and listen to headphones. I am very hot on Nuforce based on my HDP experiences however, so I'm curious if the DDA-100 is enough to drive my speakers. They are 83dB, but I get the impression that the 'si' model is easier to drive than the original model, which I have also had when I was an all-tube guy. 

Any thoughts on that?

Another option, I suppose, would be to keep my RB-991 a while longer and simply go for the DAC-80. Did you have a chance to listen even more to it, or are your comments above on it still what you feel? My reason to consider the DDA-100 is that I'd love to simplify my setup if possible, as I nowadays soley play music from my iMac. Do you also happen to have any experiences on the sound profile of the HDP vs. the DAC-80/DDA-100?


John Grandberg's picture

I think you are exactly the type of user NuForce was aiming for with the DDA-100. Simplify the system, get that massive Rotel out of there, and have no need for a separate pre. I think the DDA-100 would offer a step up in terms of clarity, microdetail, and general "realism" as most people define it. The caveat - you're used to having 200wpc to play with, and would now have just 1/4 of that.

It would really come down to your listening habits. If you, like me, tend to listen at reasonable levels in the mid 80dB range, and don't have a massive room, the DDA-100 should work beautifully. If you're one of those people who demand really high volumes at all times, you may find the DDA-100 lacking in dynamics. 

It's been a while since I heard the HDP. I remember liking the detail but also finding it slightly bright/aggressive. But that was mainly as an integrated headphone amp - not sure I ever used it as a pre. 

Trasselkalle's picture

The room is quite big, I have to say (closer to 450 sqft [40-45 sqm] and two-story ceiling), but I normally stay as low volume as is needed for the speakers to really open up. My HDP never goes over 50% with the Rotel. I'm also a bit worried as my old M3 (i.e. not the 'si' I have now) were a bit sloppy in the low end when I ran tube amps, but this tightened up when I went to solid state power amp with suffiecient power. 

Dynamics are important to me, but not in terms of pure volume. I'd say it's more in terms of how quickly (and effortlessly) music shifts from the most delicate to the more powerful (pp to ff) without losing grip of things. In my world those passages are often what separates the decent (musicians as well as hifi gear) from the great. 

I must also ask: Do you feel the DDA-100 is likely to be a suffiecient step, rather than go for a DAC-80 + possibly new power amp? Heck - the DAC-80 and STA-100 are nothing in price compared to what just my old tube amp ran. Still, simplification is highly attractive and the fewer steps where things can go wrong... On the other hand, that 192 asynch of the DAC-80 is also looking attractive, together with the fact that it would be a 'safer' option in case I feel the amp is a tad weak. 

John Grandberg's picture

Sounds to me like you might be right on the edge between the DDA-100 working and not being adequate. A safer bet would probably be the DAC-80 paired with the STA-100. It gets you almost all the benefits of the DDA (still doesn't quite have the same level of intensity with micro detail) but with considerably more power on tap. Or else try DDA first and see - I'm sure you can find it from a retailer who allows a 30-day in home trial. 

Trasselkalle's picture

Thank you again. I think the gut feeling should not be ignored, so I'll have a go at either the UDH-100 or DAC-80 (I understand they are the same in terms of DAC and pre-amp) and the STA-100. That also gives me the option to upgrade the pre-amp by adding a HAP-100 at a future date.

But no... this didn't simplify as I had hoped. It feels safer though, so thanks! Great reviews overall, also, John. Keep them comming :)

pixelatemyface's picture

Is there a quick and easy way to determine the version number of my DDA-100? Does anyone know if there is a reference that lists the range of serial numbers for each version?


jswansong's picture

I've not yet been disappointed following the subjective opinions of the writers here, be it Tyll, John, or ljokerl.


However, I must point something out here.  The 'analog' nature of PWM amplification is either a misnomer or misunderstanding.  While the PWM technology itself is allows for any duration between switching between the on and off states, in any implementation of the technology, the duration is governed by a digital clock.  In the case of the DDA-100 (where the upsampled refresh rate is 3 gigabits per second), the duration between switches must be a multiple of 1/3 billionth of a second.  That is mighty impressive and, for all practical purposes, indistinguishable from infinitely variable duration.  But it is, without question, digital. The duration between switches is a multiple of the clock speed, and the value can only be on or off, the very definition of digital.  Anyone telling you otherwise (including Nelson Pass, whom I respect immensely) is either trying to allay your fears of 'digital-sounding' music, or misunderstands the details of the technology or its implementation.


Thanks again for all the invaluable impressions you publish here.