Product: NuForce Icon - class-D integrated amplifier & USB DAC
Manufacturer: NuForce - USA
Cost: 171 UKP (YMMV)

Reviewers: Nick Whetstone - TNT UK & Lucio Cadeddu - TNT Italy
Reviewed: July, 2009

icon (REPRESENTATION)
noun [C]
a very famous person or thing considered as representing a set of beliefs or a way of life.

It's quite a brave thing (even for a marketing man) to choose the name 'ICON' for a product! That product is bound to come in for some very close scrutiny to see if it comes up to the claims made for it.

When the NuForce ICON arrived, it was clear that even the packaging is meant to re-affirm this image of the ICON as, well an icon. The packaging is slick, much more than just a protective container for what is inside. I can imagine kids being quite proud to walk home from a store with the Icon package. And when the package is opened, what's inside is no less impressive. The ICON itself is a beautiful bit of miniature engineering. The subtle but quite sexy aluminium case with those rounded edges invites you to hold it. It's very tactile. Everything looks just 'right'. The size of the knobs, the proportions of the case, the colour, and even the neat little stand. There is one source selector knob and one for controlling the volume that doubles up as the power switch. The sample sent to me for review was a very nice metallic red, but the ICON is available in other colours: blue, black, or silver. And that nice little stand is made from solid aluminium and holds the ICON very securely in an upright position so that it takes up the minimum of space on a desk or shelf.

It was no mean feat to get all the sockets on that tiny rear panel, and the designers had to pull a trick or two out of the hat. Conventional binding posts for the speaker connection would have taken up most of the available space on their own so they were ditched. A pair of RJ45 sockets (more commonly used for Ethernet connections) were used in their place. This meant that NuForce had to include their own speaker leads (1.2 metre or 2 metre) with the ICON, with RJ45 plugs on one end, and the more usual standard banana plugs on the other. This of course makes trying your own speakers leads rather complicated because even if you could solder up some leads with RJ45 plugs on them, you would be quite limited as regards the size of wire that you could fit into those plugs.

There are three different types of input on the ICON, standard RCA, USB, for connection to a computer, and a jack socket to connect up something like an MP3 player. As you may have guessed, being able to connect the ICON directly to a computer means that it has an internal (USB) DAC. This should be kept in mind when comparing its price to another class-D amp without the USB facility built in. There is also a headphone output socket on the front of the ICON, as it can also be used as a headphone amplifier. Quite a versatile little device!

The ICON is quite easy to set up but there are a couple of points to mention. The supplied speaker leads are not very long. I would guess they have been designed to be used with desktop speakers. If you want to use the ICON in a full-sized room system, with the speakers in their usual positions, you will probably need to extend the cables. I did this for the purposes of this review. The ICON has an external SMPS that accepts a mains lead with IEC plug. There is an umbilical lead to the power socket on the rear of the ICON. I expect that it was not possible but in an ideal world the power socket would have been better located at the bottom of the amp (as it stands in the vertical position) than the top where it inevitably trails over the speaker cables.

I started off with the ICON connected via the RCA input to a Monica3 DAC fed by a modified Logitech SB3. Speakers were my very efficient modified Mordaunt Short Pageant II's at 95 db efficiency and very easy to drive. Even with these speakers, I had to turn the volume control on the ICON to maximum, and even then it wasn't really loud enough. So I added in the Audiodigit Tube-Pre to get a bit more gain. Things were slightly better all round with the Tube-Pre in the system but maximum loudness was no more than 'comfortable'. This was quite frustrating as the sound quality was clearly very good. That Class D clarity was there in what was a fairly laid-back relaxed presentation. Once the Tube-Pre was added, the sound stage expanded from 'hanging' between the speakers to spreading right across the room. On acoustic music the sound was very nice but on some tracks I felt the tone was a bit on the thin side. For instance, with the opening guitar solo on the Eagles' 'Hotel California', the guitar sounded a bit more like a banjo!

I decided to move on and try the ICON with the computer. The PC in question was an older Pentium III running Ubuntu, and using Exhaile as the music player. Of course, the PC connected directly to the ICON so the Tube-Pre was no longer in circuit. I found the USB connection preferable to the RCA connection but there simply wasn't enough gain, even with the volume control on the PC set to maximum. The sound quality was very good though, clear, great timing, good sound-stage, not bad bass, but simply it wouldn't go loud enough. Although what I could hear of the bass was OK, the whole sound lacked weight at the volume levels I was listening at. As a headphone amplifier the performance was quite satisfactory, particularly through the USB connection.

So my conclusion on the ICON is that has been designed for a high quality desktop system (ie near-field listening), rather than for going in a room system. Perhaps this is why the supplied speaker leads are comparatively short. In fact, I utilised the compact size of the ICON to have it sitting on my workbench where it served very well with a small pair of speakers (salvaged from a Pioneer mini-stack system) to test other projects. That did seem a bit ignominious for such a beautifully designed piece of equipment but with that lack of output, I couldn't find a better use for it - and that was very frustrating given what I heard it producing!

© Copyright 2009 Nick Whetstone - www.tnt-audio.com

Lucio Cadeddu's listening notes

These two reviews were written simultaneously but independently, so to not influence our findings. As you're going to discover, our conclusions are a bit different, especially in relation with the power output of the amp. These proves, once again, that when one deals with low-powered amps, it is of paramount importance to choose the right ancillaries. Different speakers might lead to very different results. For this reason, especially with these products, we strongly recommend private tests with your own speakers before any purchase.

Having tested almost any NuForce amplification in the past years I assume to be quite familiar with their "family sound". For this reason I was very curious to test their small Icon integrated amplifier based on a proprietary NuForce Class D chipset. You might have already read my opinion during the comparison review of the Scythe SDA-1000, Trends Audio TA 10.1 and NuForce Icon.

First, let me add a few lines to integrate Nick's description. It is true that the speakers leads supplied with the Icon are short but NuForce sells a sort of a "connection box" (called RJ45CX), the same size of the Icon, where you can connect any kind of speaker cables terminals (bananas, forks and bare wires). Just hook up the Icon to its connection box (via the CAT5 supplied cables) and you're ready to use ANY cable you want. This way you can normally use the Icon as any other standard integrated amplifier.
Secondly, NuForce supplies the configuration scheme of the RJ45 connectors (see pic at the bottom of this page). This way you can cut the CAT5 wires and connect any kind of cable directly to the RJ's (for example installing two pairs of banana females).
Thanks to the connection box I've been able to use my standard speakers cables with the Icon.

I've used the Icon in my main system, with different CD players and DACs and I've found its gain to be completely adequate. Indeed, clipping was normally reached at 12 - 2 o'clock volume position, depending on records. Using it directly connected to the USB port of my notebook things were a bit different and volume settings, in order to get the same pressure levels, were closer to maximum.
These are the claimed tech specs:

• Inputs: RCA; USB (USB 1.1, 2.0 compatible); 3.5mm Stereo minijack
• Speaker Outputs (RJ45 connectors with 15 micron thick gold plating). NuForce RJ45 to banana plug speaker cables are provided with NuForce Icon.
• Headphone Output:
  • Maximum output @32 ohm Load: 31.25mW
  • THD (20Hz ~ 20KHz) : < 0.03%
  • Frequency Fresponse (20Hz ~ 20KHz) : < -1dB
• Line Out (for Subwoofer) connection
• USB DAC: USB 1.1, 2.0 compatible. USB native bit rate: 32-48kHz, 16-bit
• Power = 12WX2. Peak power =15WX2
• THD+N=0.05%, 1kHz, 2W @ 4 ohm load. THD+N=0.06%, 1kHz, 2W @ 8 ohm load.
• Power Bandwidth: 26Hz ~ 50kHz, -1dB, 1W @ 4ohm load
• SNR = 84 db at 7W @ 8ohm
• Maximum sampling rate: 48kHz
• Resolution: 16-bit
• S/N Ratio: 98dB
• Power Adapter - 12-14V, 25W, 100-240VAC worldwide voltages
• Dimension: 6" x 4 1/2" x 1"
• Weight: 1 lb. Shipping weight 5 lb.

Soundwise, I've found the NuForce Icon quite impressive. Staying within its low power output capabilities it delivers a solid and competent musical performance, with very good bass and smooth mid-to-high range. Somehow, the Icon possesses some of the virtues of its bigger brothers, for example the ability to sound effortlessly even when reproducing complex musical patterns (many instruments and voices at the same time).
It sounds dynamic and, provided the speakers have an adequate sensitivity and the room isn't too large, it is easy to "fill" the room with its sound. For example, in my 18/20 sqm room and with 90 dB speakers the sound pressure at the listening seat is near 100 dB (peaks, measured with a digital SPL meter). Many audiophiles can't exceed, because of their intolerant neighbourhoods ;-), 90-95 dB or so. Perhaps Nick exceeds 110 dBs or so during his listening tests (me too!), for this reason he might have found the Icon slightly underpowered :-)
NuForce also sells a beefier 42 watts power supply for some extra dynamic headroom (+45$, not tested). The standard PSU is rated at 25 watts (1.6A).

The Icon can also generates a very good and wide soundstage, though not as deep as the one created by the Trends Audio TA 10.1. The virtual 3D scene is quite large, while instruments and singers appear very nicely focused and stable. Being designed as a desktop amplifier this particular aspect shouldn't be relevant (who cares about soundstage on a desktop after all?) but I believe the Icon deserves to be considered (and tested) like any standard integrated amplifier. For this reason I hope NuForce will release a version of the Icon with standard speakers binding posts, and add another line-level input in lieu of the USB one.
The RJ45CX outboard connectors box might be a good idea but it is expensive (100$!!!), adds unnecessary cables and points of contact on the signal path and it doubles the size of the Icon! A slightly larger cabinet with banana/forks/bare_wire binding posts would have been THE solution. The longer 2 meters speaker cables (+30$) might make things easier but standard lenght for most HiFi applications is 3 meters! Moreover, audiophiles prefer to use their speaker cables (which already own, normally).
The easiest solution for the "connection" problem would be an RJ45/banana adapter, a connector with male RJ45's at one end and standard banana/forks/locking post females at the other. I'm sure this can be made quite easily (even DIY). For example one can cut a short run of cat5 cable (1 cm or so) and solder it to standard binding pots (some heatshrink tubing might help here). Of course, thanks to the connection scheme displayed below you can even build your own speaker cables.

Conclusion

Actually, I liked the Icon very much. Considering its selling price (249$) it has a lot to offer, especially when compared to its natural competitors: two line level inputs, an inboard USB DAC (hence a third input!), headphones and LINE OUT output, cool looks and superb finishes. If you're using a PC as main source for your stereo system this amp should score high on your wish list. Its sound reminds me that of its bigger brothers (transparent, precise, effortless) so much the Icon can represent an excellent way to build a fine HiFi system without breaking the bank.