Although NuForce offers a full line of electronics, headphones, cables, and even modifications of Oppo Blu-ray players, I associate the brand with high-end, class-D power amplifiers. A few years ago NuForce launched a line of inexpensive desktop components that included some snazzy little models for only a few hundred dollars each, such as microsize integrated amps and headphone amps, both using their proprietary class-D amplifier design. While these components made NuForce products more accessible to audiophiles on a budget, there was a gap between their low-cost desktop and audiophile lines.

Enter NuForce’s new integrated amplifier, the DDA-100, for only $549 USD. Although relatively compact, the DDA-100 is claimed to provide a respectable 50Wpc into an 8-ohm load. Though this makes it more suitable for full-size than for desktop systems, the DDA-100, like many of NuForce’s desktop amplifiers, accepts digital signals via USB and S/PDIF inputs, making a high-quality outboard digital-to-analog converter (DAC) redundant. Add a pair of high-quality budget speakers, use as a digital source a laptop computer (which most people already have anyway), and this digital integrated can be the centerpiece of a cost-effective audio system.

Direct Digital . . . and Direct Digital only

The DDA-100 offers a lot for its reasonable price, but I’d be lying if I said that I fully understood how NuForce’s amplifiers work. What I do know is that, like all of their amplifiers, the DDA-100 uses their own proprietary, IC-based, class-D switching technology. Like many integrated amplifiers these days, the DDA-100 accepts digital signals directly from source components via S/PDIF and USB inputs. However, it lacks a conventional DAC stage, leaving the signal in the digital domain until just before its speaker outputs. There are other examples of this type of amplifier design, such as Wadia’s 151PowerDAC Mini and NAD’s Direct Digital components, but the DDA-100 costs much less.

The “DDA” in the model name stands for Direct Digital Amplifier: the DDA-100 accepts only digital signals. Its USB type-B input can receive signals of resolutions up to 24-bit/96kHz, and it also has two optical and one coaxial S/PDIF input, and an optical output. The S/PDIF inputs can accept signals with a maximum resolution of 24/176.4, but not 24/192. Another limitation is that the USB input can’t accept signals with a frequency of 88.2kHz -- a problem if you have a lot of digital files at this sampling frequency. The USB input is adaptive rather than asynchronous, which could theoretically result in greater jitter, though the DDA-100 has an “on-chip clock reference signal for synchronizing incoming digital audio data” that NuForce claims results in lower jitter. The DDA-100’s output of 50Wpc into 8 ohms is much more than the 18Wpc of their tiny desktop components, which are based on their smallest amplifier module. One thing the DDA-100 lacks that many of NuForce’s desktop components have is a headphone output. It being an all-digital component, this is understandable; it would have needed a separate DAC stage just for the headphone jack.

The DDA-100 measures only 8.5”W x 2”H x 9”D and weighs 2.64 pounds, but feels quite solid. On the rear panel are speaker binding posts of decent quality, spaced far enough apart to accept relatively large connectors such as spades; an IEC power inlet that allows the use of aftermarket cords; and the main power switch. The case has rounded edges and is nicely finished in a slightly textured paint available in matte black or silver. On the faceplate, a single knob/button controls all functions. Pressing this knob turns on the DDA-100, pressing it again changes the input, and holding it down a few seconds turns the power off. There seems to be no display at all until the DDA-100 is turned on, when a screen of tiny red LED dots becomes visible. Two characters indicate the active input, and two digits indicate the volume setting. A tiny remote control, its buttons covered with a plastic membrane, is provided. I don’t like the feel of such buttons, but at least a remote is provided, which is more than can be said for many small, inexpensive integrated amplifiers. The remote worked fine, but I preferred to use an old RF learning remote that I had lying around and was able to program to work with the DDA-100.

Setup

I used the DDA-100 primarily with a pair of Definitive Technology StudioMonitor 45 speakers and an Acer Aspire One 770 netbook computer running Windows 7 and foobar2000. The rest of the system comprised an Oppo BDP-93 Blu-ray player, AudioQuest Carbon USB cable, DH Labs D-75 digital cable, Analysis Plus Clear Oval speaker cables, and ESP MusicCord Pro-ES power cords. The DDA-100 also spent some time with a pair of Definitive Technology BP-8080ST speakers and an NHT speaker system of SuperZero 2.0s and Super 8 subwoofer. Like other USB-capable audio devices I’ve used recently, the NuForce DDA-100 was immediately recognized by my computer. I then set foobar2000 to WASAPI output, and the system worked without incident throughout the listening period.

One thing to keep in mind when using the DDA-100 in a system that’s used to watch television: some smaller, less expensive TVs lack a digital audio output, as do, obviously, older analog sets. No problem, you say? You can just use your cable box’s digital audio output? I thought the same thing -- but the digital audio outs of my Motorola PVR can output only Dolby Digital bitstreams, which the DDA-100 doesn’t recognize.

Forceful performance

Any minor criticisms that I might have had of the DDA-100’s ergonomics and features quickly disappeared when I started listening. I was immediately won over by its spectacular performance. Listening to the ridiculous “Gangnam Style,” from Korean singer Psy’s 6 Gab, Pt. 1 (16-bit/44.1kHz FLAC, YG Entertainment), the soundstage was restricted to a relatively narrow space between the speakers, but within that stage the imaging was incredibly sharp. The NuForce had enough power to keep the bass fast and punchy, and provided very clean sound even at high volumes. The nonsensical lyrics were plainly intelligible (I don’t speak Korean, but even if I did, I imagine that the lyrics would still be nonsensical), the repetitive dance beat was always catchy, and there was even a nice sense of depth.

The 2012 remastering of Peter Gabriel’s So (24/48 FLAC, Society of Sound) sounds a bit thin, as do the previous versions, including the Geffen/Universal SACD, but I heard more detail and clearer sound from this latest version through the DDA-100, which did an excellent job of reproducing it. The intricate arrangement of “Red Rain” had a sense of scale and dimensionality that was as good as I’ve ever heard with this track. The piano notes in the alternative version of “Don’t Give Up” trailed off into the darkness of the expansive soundstage, and Kate Bush’s backing vocal had a purity that was light and ethereal. While the rest of the tracks sound similar to previous masterings, the remix of “Don’t Give Up” was a refreshing take on the original, and especially enjoyable through the DDA-100.

The Definitive Technology StudioMonitor 45 is a beefy little bookshelf speaker that can play surprisingly loud, and with the NuForce DDA-100 it did not want for power. Daft Punk’s “Solar Sailer,” from the Tron: Legacy soundtrack (16/44.1 FLAC, Walt Disney), had a deep soundstage and enough low bass to fill the room. In fact, there was so much bass that it was hard to believe it was coming from two bookshelf speakers driven by such a low-priced little amp. The Japanese SHM-CD (Super High Material Compact Disc) version of Fields of Gold: The Best of Sting 1984-1994 (16/44.1 FLAC, Universal) had good slam. The bass line of “We’ll Be Together” was taut and punchy, voices were clear, and each shake of the tambourine was remarkably distinct and lifelike. The rich orchestral arrangement of “Russians,” laden with rumbling timpani, clashing cymbals, and other percussion, was spread evenly between the speakers.

Judging by the DDA-100’s authoritative sound, I wouldn’t have been surprised had I learned that it cost twice its minuscule price, or even more. But there was more to this little amp than just commanding bass and dynamics. Eva Cassidy’s voice was sweet and expressive from the Japanese XRCD24 version of her Songbird (16/44.1 FLAC, Blix Street). The DDA-100’s ability to reproduce the complexities of the human voice with a sense of ease and naturalness was always inviting and thoroughly enjoyable. Listening to Cassidy’s soulful rendition of Curtis Mayfield’s “People Get Ready,” her varied vocal phrasing and her uncanny ability to lead the music’s ebb and flow was exquisitely reproduced by the DDA-100. I was swept away by the musicality of the sound, which brought back a flood of memories of when I first discovered this recording and the world of high-end audio. I just wish I’d had so capable an amp at the time, and for such a reasonable price.

Dueling digital

While the DDA-100 might have lacked a few features I would have liked, I found it difficult to criticize its exceptional performance for the price. In comparison, NuForce’s Icon-2, a small desktop class-D integrated amp, costs only $349, has analog inputs, and a single digital input on USB, but lacks a remote control. While I loved the Icon-2’s small size, its 18Wpc couldn’t compete with the DDA-100 in terms of power or fidelity. Even at moderate output levels, the Icon-2 sounded slightly constrained, and couldn’t drive the DefTech StudioMonitor 45s to the levels I’d become accustomed to with the DDA-100. Cyndi Lauper’s voice on her The Body Acoustic (16/44.1 FLAC, Sony) is miked very closely and is difficult to reproduce, especially when she strains to reach notes close to the top of her range. When this occurred, the Icon-2 sounded a little edgy as it struggled with this unforgiving recording. The DDA-100 didn’t unnaturally smooth out Lauper’s voice, but it did provide a cleaner reproduction of it. Eva Cassidy’s voice on Songbird sounded smooth and effortless through the DDA-100, but slightly congested with the Icon-2.

The DDA-100 drove the StudioMonitor 45s to satisfyingly high levels with “Seven Drums,” from Dadawa’s Voices from the Sky (16/44.1 FLAC, Warner). When this track’s massive drumstrokes were unleashed, there was some surprisingly low bass with good control for such a small budget amplifier. Pushing the DDA-100 to even higher levels, levels that were actually near the DefTechs’ limits, the amp did begin to clip; in comparison, the Icon-2 couldn’t even come close to playing this track at such high levels.

Inserting into the system the much more expensive and excellent-sounding Bel Canto Design e.One C5i integrated amplifier ($1995) yielded further improvements. However, the differences weren’t as marked as when I directly compared the two NuForce designs. The C5i, another class-D amp, but one using ICEpower modules and a conventional DAC stage, had a noticeably more powerful and controlled sound than the DDA-100, even though its power rating is only slightly higher, at 60Wpc into 8 ohms. The C5i was able to play louder with greater composure, reproducing the timpani in Sting’s “Russians” with a tighter grip and more realistic-sounding and well-defined cymbals, which could sound a little splashy through the DDA-100. Although the C5i had better control at high volumes, the DDA-100 was otherwise quite close in performance to the Bel Canto, which costs almost four times as much. The C5i also has more features, including an analog input that can be used as a home-theater bypass, something I find invaluable for integrating preamps and integrated amps into a multichannel audio system. It also has a moving-magnet phono stage, a headphone jack, and can support sampling rates up to 96kHz over USB and up to 192kHz over S/PDIF.

If I had a few thousand dollars and was putting together an entry-level high-end system, especially one that incorporated multichannel sound, the Bel Canto C5i would be my choice for its complete feature set and superior performance. However, considering that the NuForce DDA-100 costs not much more than a quarter the C5i’s price while coming relatively close to the Bel Canto’s high level of performance, it must be considered an incredible bargain for anyone looking to assemble a great-sounding, digital-only, two-channel audio system.

Conclusions

At only $549, the NuForce DDA-100 sets a new standard for performance in an affordably priced integrated amplifier. Sure, it accepts only digital signals and has some quirks, such as the inability to accept 88.2kHz signals over USB, but you’d have to spend a lot more to significantly improve on its sound. If you can live within those limitations, I can’t think of a better way to provide amplification for a truly high-end system at a paltry price.

. . . Roger Kanno
rogerk@soundstagenetwork.com

Associated Equipment

• Speakers -- Definitive Technology StudioMonitor 45 and BP-8080ST, NHT SuperZero 2.0 and Super 8
• Integrated amplifiers -- Bel Canto Design e.One C5i, NuForce Icon-2
• Sources -- Oppo BDP-93 universal Blu-ray player, Acer Aspire One 722 computer running foobar2000
• Cables -- Analysis Plus Black Oval 9 speaker cable, DH Labs Silver Sonic D-75 digital interconnect, AudioQuest Carbon USB cable
• Power cords -- Essential Sound Products MusicCord-Pro ES
• Power conditioners -- Blue Circle Audio Peed Al Sea Thingee and 18X Sillycone Filter, Zero Surge 1MOD15WI

NuForce DDA-100 Direct Digital Integrated Amplifier
Price: $549 USD.
Warranty: Two years parts and labor.

NuForce, Inc.
382 S. Abbott Ave.
Milpitas, CA 95035
Phone: (408) 890-6840

E-mail: salesteam@nuforce.com
Website: www.nuforce.com