While computer-based audio offers many sonic and programming
advancements over disc-based systems, it also brings greater level of complexity
to a sound reproduction system.
As a reviewer, computer audio manages to be both easier and
harder to cover. It’s easier because you can, if you’re clever, set up robust
matched-level A/B comparisons between DACs and other components. It’s harder
because you have far more variables to consider in making sure all components
are operating in their maximum performance range. Reviewing a USB 2.0 compliant
DAC using a USB 1.0 pipe ain’t gonna cut it.
When I first set up a USB DAC I try it with iTunes, Amarra,
Pure Music, Audirvana Plus, Decibel, and even Preview. On more than one occasion
I’ve served as in inadvertent Beta-tester. Recently I discovered an issue
between Audirvana Plus and a USB DAC that caused the DAC to generate spurious
noise when put into a software-induced mute mode. The manufacturer hadn’t used
their DAC with Audirvana Plus, so the problem was as much of a surprise for
them as for me.
As a Mac user, one essential program is the Audio Midi Setup
control pane. The Midi Control shows what audio devices are attached to your
computer and what sample and bit rates they support. You can see current
bit-rates and change them as needed. The Midi control also shows whether a
device is muted and its current volume level. Many problems with volume, mute,
or bit-rates can be easily solved with a couple of mouse-clicks in Midi control.
Another essential, but little-used program in the Mac is the
“About This Mac” option, found under the Apple symbol in the left hand upper
corner of your screen. Under “More Info” you’ll see vital information about
your USB chains that will show what devices are connected where and which USB
protocols are being used with each one. The illustration to the right is the
information pane from my Mac Pro desktop computer. If you look at the device
list under “USB High Speed Buss” you can see that all three of the DACs
currently connected are on the same buss. When I choose one, I can be sure it
will get the same quality data stream as the others.
Although many computer audio products are advertised as “plug
and play,” the reality for a committed computer audiophile is there’s no such
thing as plug and play – even if a device seems to be working perfectly you
have to check the details to make sure its operating optimally. For those
audiophiles who have been avoiding computer audio because of this additional complexity,
the bad news is I don’t see this necessary level of rigor changing anytime
soon. The good news is that most of the steps needed to insure optimal fidelity
don’t require very much time or physical effort – merely consistency. But consistency, especially in computer audio, requires constant
attention to detail. But if it were easy, it wouldn’t be as much fun…