NuForce Icon iDo Apple-Compatible DAC/Headphone Amp (Playback 56)

Apple Audio Unbound

I’ve been getting a number of inquiries of late from readers wanting to know if anyone makes a good, Apple-compatible DAC/headphone amp that sounds good, yet sells for a reasonable amount of money. The challenge, here, is that you can get individual products that meet some, or even most, of the requirements referenced, but that almost no one has been able to pull them all together in one accessibly-priced product—until now. Just recently, I received a sample of NuForce’s new Icon iDo ($249), which fits the bill to a “T”.

In simple terms, the iDo is an Apple-compatible, 24-bit, USB Host Mode DAC (maximum resolution, 48kHz/24-bit), coupled with a simple but very high-quality desktop headphone amplifier. Two unexpected but welcome detail touches are that A) the iDo is compatible with—yet does not require—Apple’s option remote control, and B) the iDo DAC section not only provides the expected stereo analog audio outputs but also provides a coaxial S/PDIF digital output. The upshot of this latter feature is that, while the iDo can of course serve as a perfectly satisfying DAC/amp in its own right, it can also be used as a “bridge product” that can pass jitter-reduced digital audio signals from an Apple device on through to a much higher-end DAC, if desired.

At the end of the day, though, the real reason to look into how much music from an Apple device can sound when you bypass Apple’s low-cost digital and analog audio circuits altogether, and let a much higher performance outboard DAC and amp handle the job. Readers will rightly ask if going to an outboard DAC/amp really makes all that big a difference (if, indeed, it makes any difference at all). The simple truth, as you’ll learn in this review, the iDo not only makes an audible difference; it makes a hugely audible difference that—once experienced—is pretty hard to resist.

OVERVIEW

Consider this DAC/headphone amp if:

• You want an affordable, sonically compelling USB Host Mode DAC that is geared specifically for use with a wide range of Apple devices.
• You’d like an Apple-compatible DAC that not only has analog outputs, but also provides an S/PDIF digital output.
• You also want an affordable headphone amp that works with a broad range of headphones and earphones.
• You want to see just how much better the audio data stored on your Apple device can sound when you bypass Apple’s low-cost electronics and let a high quality DAC/amp shoulder the workload (trust us on this one; the difference is pretty darned shocking).

Look elsewhere if:

• You were hoping for a highly versatile multi-input DAC; this one provides a USB input specifically for use with iPods/iPhones, and iPads (i.e., it’s not a general purpose USB input).
• You were hoping for a DAC with support for high-res 96/24 or 192/24 digital audio files; this one supports a maximum data rate of 48kHz at 24-bit resolution.

Ratings (compared to similarly-priced DAC/amps)

• Tonal Balance: 9.5
• Clarity: 10
• Dynamics: 10
• Output Flexibility: 9.5
• Value: 10

FEATURES/TECHNICAL HIGHLIGHTS

• The iDo is an Apple device-compatible DAC that supports the following Apple products:

o iPod touch (3rd and 4th generation)
o iPod classic
o iPod nano 6h generation)
o iPhone 4
o iPhone 3GS
o iPhone 3G
o iPad 2
o iPad
o NuForce advises that, “only iOS3 and later version are supported.”

• DAC provides “bit-perfect, low jitter USB Host Mode operation.” The significance of this feature is that the iDo—not the Apple device—controls data transfers from the iDevice to the iDo and thus is able to bring the iDo’s superior low-jitter clocking capabilities to bear. Does it make an audible difference? Yes.
• The iDo uses a 24-bit DAC and supports digital audio files at up to 48kHz rates at 24-bit resolution. A footnote in the iDo manual explains that, “the maximum sample rate currently supported by Apple is 16-bit/44.1kHz or 24-bit/48kHz.”
• Unlike some Apple-compatible DACs, the iDo provides both analog and S/PDIF digital outputs, meaning that if the user would like to a higher-end DAC than the iDo (such as one from NuForce’s High-End product line), it is easy to do so.
• The iDo provides a high-quality onboard headphone amplifier that, says NuForce, “drives headphones up to 300-Ohm (12 mW@300-Ohm).” The amp provides a “digitally controlled analog volume control.” Note, too, that the volume control also sets output levels for the rear panel-mounted stereo analog audio outputs, meaning the iDo can also be used as a preamplifier.
• The iDo is housed in the familiar, attractive, slim-line (6” x 1” x 4 ½”) metal case used for most of NuForce’s desktop audio components.