NuForce Icon HD User Manual page 5

DAC and Headphone Amp User Guide
Introduction
CD-ripping software is capable of reproducing "bit perfect" digital music data (16 bit/44.1kHz) from audio
CD files stored on the computer's hard drive. In addition to CD-quality music, some online sites are now
offering 24 bit/96kHz music files. Thanks to larger and increasingly economical hard-disk capacity,
consumers can store the highest quality music files on their computers. However, extracting good sound
from the computer poses problems.
Poor Sound Quality
As a rule, your computer's audio doesn't sound quite right because computer manufacturers often treat
their products' audio output stage as little more than a necessary evil. So long as the music signal remains
in a digital format, all is well. The pitfalls appear when the computer converts signals to analog, which is
how we listen to music. Typically, the onboard converter (a.k.a. sound card) is a low-cost item. Digital
circuitry generates noise that often bleeds into the audio stage. Further, these compromised stages are
seldom designed for the low-impedance power high-quality headphones require. Finally, should you use
the computer's software to reduce volume, you may actually be listening to eight-bit resolution –– in real-
world terms, not at all good.
In sum, these deficits conspire to produce inferior sound. Far better to send the digital signal to an external
digital-to-analog converter (DAC). NuForce Desktop products employ quality DACs.
Digital Connections
There are two methods for extracting digital signals from your computer. The universal serial bus (USB)
connection is the de-facto standard for just about all peripherals: printers, digital cameras, etc. The USB
allows the computer to speedily recognize a connected device. Some computers also incorporate the
Sony/Philips Digital Interconnect Format (S/PDIF), a coaxial connection with excellent transfer properties.
USB Audio and Performance Optimization
USB specifications define a standard interface: the USB audio-device class, which allows a software driver
to work with the currently available USB sound devices. Microsoft Windows, Apple Mac and many Linux
versions provide support for USB audio devices. NuForce Desktop USB DACs convert USB digital data to
the analog signal headphones and amplifiers require. Equally as important, how the USB DAC performs
affects sound quality.
For more information on this subject, see http://en.wikipedia.org/wiki/Universal_Serial_Bus
Some Optimization Tips
To minimize noise and dropouts, connect your audio interface to a port at the back of your computer.
Generally speaking, ports on the computer's face, monitor or keyboard don't perform as well.
If you use a USB hub, choose one with its own AC power adapter. In areas that produce high levels of
radio or electrical interference, upgrading to a quality USB cable, i.e., one with extra shielding and a ferrite
bead (the cylindrical collar on one end of the cable) to help eliminate noise. Once you're properly
connected, your computer's operating system should automatically detect your NuForce product. From that
moment on, all you need to do is enjoy the music.
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