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Abit's iDome DS500 and SW510 speakers

A mobo maker dabbles in digital audio

ModeliDome DS500 (Speakers)
iDome SW510 (Subwoofer)
Price (Street) (DS500)

WHEN ABIT WAS ACQUIRED last year, the new owners pruned the company's product line to focus its attention squarely on motherboards. Graphics cards and other ancillary products were cut, but one plucky side project managed to survive. That side project spawned Abit's new iDome digital speakers and may inspire a revolution in PC audio.

That probably sounds a little melodramatic, but consider this. The iDomes were designed from the ground up with digital input in mind, and Abit has taken great care to ensure that they deliver every bit of the pristine quality of a digital bitstream to your ears. That bitstream—digital audio in its purest form—can be provided by fancy sound cards and "free" integrated motherboard audio alike, setting up the iDomes to challenge not only other speakers on the market, but the very need for a discrete sound card as well.

And so the stage is set. Can the iDomes, when paired with integrated motherboard audio, challenge the output quality of the best PC sound card on the market? Read on to find out.

Why digital?
PC audio starts in a digital format—a series of 1s and 0s that can be faithfully, and even perfectly, transmitted within the confines of a system. However, to get that audio content into a format that our ears can hear, it has to leave the safe, binary confines of the PC and enter our organic, analog world. Therein lies the problem: reproducing and transporting 1s and 0s in a digital world is a snap, but translating those bits into analog waveforms is not.

In most modern PCs, digital-to-analog audio conversion happens in an aptly-named piece of silicon called a DAC, or digital-to-analog converter. (The DAC is sometimes integrated into a cheap multi-purpose chip that acts as a DAC, ADC, and headphone amplifier, such as the Realtek ALC880. Fear the crab.) This chip sits on the motherboard or sound card and converts outbound audio bitstreams into waveforms that get piped to analog output ports. This crucial step is often where things go sideways in PC audio. Many a pristine digital audio signal has been butchered by the cheap DACs built into most motherboards and low-end sound cards.

Assuming the DAC does do a good job of converting the original audio bitstream to an analog signal, that signal is still subject to distortion on the way to the speakers. First it must pass through the confines of the PC, where it's subjected to all sorts of electrical noise that can interfere with the signal. Once it leaves the system, it has to contend with the speakers, which probably apply some form of amplification that further manipulates the analog signal.

One way to combat such distortion and interference is to move the DAC closer to the end point on an audio stream's journey. Digital signals can more easily maintain their integrity while navigating interference-riddled environments, and their very nature allows for more precise manipulation.

With the iDomes, Abit has moved the digital-to-analog conversion process right to the end of the line. Audio bitstreams maintain all their digital glory as they leave the system and enter the speakers, bypassing the DAC on the sound card or motherboard. Once the bitstream enters the iDomes, it hits a digital processing unit that handles equalizer functions and amplification. This work is all done in silicon, with a µGuru chip controlling one of several preset "SFX" processing modes.

Speakers can't generate sound waves directly from a digital signal, so the iDomes do have to dip into the analog world eventually. However, that conversion doesn't happen until the end of the line, which should help preserve the integrity of the original signal.