Made specifically for mobile Apple products this igadget unit bypasses your apple products internal DAC. It also has a built in headphone amp as well. We had two of these at our desks in our office for a number of years where they served us well. Note that the unit works with iPads, iPhones, and iPods. The Icon is all metal construction and comes with the unit, power supply and rubber stand. Working condition is excellent and physical condition is very good with some blemishes and light scratches, but no dents. See the detailed review below from the website inner fidelity.
NuForce Icon iDo USB DAC Headphone Amplifier
Oct 13, 2011
What it is
The iDo is a cute little thing -- just 6" x 4.5" x 1" -- and it shares its all-metal chassis with NuForce's other Icon desktop amplifiers and DACs. Setup is super-easy, connect any Apple mobile device to the Icon iDo with the included 30-pin sync/charging cable, plug the wall-wart power supply into the iDo, and you're good to go. If space on your desktop is tight orient the iDo vertically (it comes with a secure stand for that purpose), or lay it down. The iDo is available in black, white, blue, or red. It's $249.
Start making sense
I have to admit I didn't quite understand the logic of making an AC powered device for iPods, iPhones or iPads, so I asked NuForce's Jason Lim about the iDo's raison d'être. He explained it was designed for people who bring their Apple devices to work and want the best possible sound, but don't have access to music on their computers. If you want a USB DAC for your computer NuForce's Icon HD ($349) is the way to go. Want a portable USB powered headphone DAC/amp? Check out the Icon Mobile ($79).
The iDo's DAC is much the same as the one used in NuForce's uDAC2, but the maximum sample rate is 48-kHz, with up to 24-bit resolution. The amp has a 5 ohm output impedance and drives headphones up to 300-ohms. And yes, iDo recharges your Apple device when it's not playing music.
The connectivity quotient is decent, there's a USB input, and coax digital and RCA analog outputs. Upfront you'll find a volume control, a green digital lock LED, and a blue LED that moves along a long slot to indicate volume level. That's fine, but then I noted that when I changed the volume on my iPod Classic the iDo's volume changed. That didn't make sense, the iDo was hooked up via the iPod's 30-pin digital output, which I always think of as fixed in level. Jason Lim explained that's the way the USB Host system works, he said "The volume is always set to max on Apple mobile devices when it is connected to the iDo. The iDo will accept Apple's remote control to change the volume on Apple devices." Whatever, I used the iDo's volume control for all of my listening tests.
There's a 1/8" mini headphone jack on the front panel, but I wish NuForce had also included a 1/4" jack. The iDo will mostly be used at a desk, and sometimes with full-size headphones terminated with 1/4" plugs. Sure, you can snap on a 1/8" to 1/4" adaptor, but they can be pretty bulky. Why not put 1/8" and 1/4" jacks on the iDo?
I used a bunch of headphones, including my two Audio Technicas, the ATH-WS55 and ATH-M50, B & W P5, BlueAnt Embrace, Sennheiser HD-580, Grado RS-1, Audeze LCD-2 full-size headphones, and Jerry Harvey JH-13, Monster Turbine Gold, and Klipsch S4 in-ear monitors for my testing. My iPod Classic was the only source for the listening tests, and most of the music was encoded in Apple Lossless. Even with the super efficient JH-13 in-ears the iDo was dead quiet, and added absolutely no noise or hiss. The iDo worked its magic with most of the headphones, but it was less terrific with the Audeze LCD-2. There the sound was thin and I felt the iDo was out of its comfort zone. The AT-M50 was the primary headphone for the bulk of my listening time.
On to the listening ...
Somebody gave me a burned CD by a string quartet that goes by the name Ethel. They play contemporary music, and their muscular workouts and visceral rhythms set my head a bopping, so much so I forgot to take notes on the finer aspects of the iDo's sound. That's always a good sign.
Keith Richards' reggae albums with the Wingless Angels had a satisfying weight and depth with the iDo. Returning to listening via my iPod's headphone jack and internal DAC was a severe letdown and robbed the 'Angels of their organic feel and flow. The sound of the voices, drums and guitars hardened and the music's power took a nosedive. The soundstage wasn't any wider with the iDo, but it felt more spacious when the NuForce was on the job. To put it another way, the iDo made most of the headphones sound like better, more expensive headphones.
The Black Keys' "Brothers" album is always in heavy rotation on my iPod, and the iDo delved deep into the 'Keys' garage blues bliss. Bass was deep, punchy, and nicely controlled; the fuzzed-out guitar textures had just the right flavor of grit. Tasty, very tasty indeed.
Later on, I compared the iDo with my DACport USB DAC/headphone amp while playing iTunes on my Mac mini. I have to say the two DACs sounded very different. The DACport's sound with the solo drum tracks from the "Best of Chesky Jazz and More Audiophile Tests, Volume 2" sampler CD was fuller, richer, and more dynamically alive than what I heard from the iDo. The 'Do had a leaner tonal balance, but it seemed to have better resolution of fine detail than the DACport. All in all, I preferred the DACport, but the iDo wasn't totally clobbered by the comparison.
I also used the iDo as a "dock," with its coax digital output feeding a PS Audio Perfect Wave DAC in my high-end system. The iDo's coax digital output bypasses the NuForce's internal DAC, so it's a straight connection between the iPod and the PS Audio DAC. Right, the iPod never sounded better. The iDo can also be used as a preamp and its RCA outputs can feed a power amp or powered speakers, like my little Audioengine A2s.
So the iDo does a lot of stuff right: it sounds sweet, takes up precious little desktop real estate.