(Reprinted from the Fall 2004 Audio Ideas Guide)

      Without this little PCMCIA card from Echo Audio I might never have heard all that these speakers were capable of. Designed to work with any Windows or Mac notebook computer, the Indigo allows the user to bypass the computer’s built-in audio output, which, in a machine designed to do a great many different things besides playing music, is usually an afterthought.

     More than just a headphone jack (the Indigo actually has two 1/8″ gold plated mini jacks) the Echo Audio card is a D to A converter as well as a high quality analog output stage. It supports up to 24 bit, 96 kHz signals, uses a 100 Mhz Motorola DSP chip and has a nice, chunky analog volume control knob right on top. For those looking to use their notebook as a recorder, Echo also makes an Indigo with an analog input as well as a model aimed at DJs, featuring two independent stereo outputs.

     Setup on my Powerbook was very easy, consisting of installing a driver from the supplied CD and sliding the card into the slot on the side of the machine.

     I listened through the Indigo when evaluating the powered speakers reviewed for the Fall 2004 Issue above, as well as with headphones, and consistently liked what I heard. Even on a pricey laptop designed for high performance multimedia like the G4 Powerbook, the improvement over the stock headphone output was not subtle. Resolution, and overall solidity improved significantly, giving the sound more coherence and bottom end grip. Back and forth listening with my dad’s fantastic sounding Grado SR 125 headphones really helped me get a handle on the improvements in the bottom end, the Indigo sounding rich, tuneful, tight and composed by comparison. In the top end I heard much more fine detail and, as a result, got much more spacious sound with subtle ambient cues intact. The sound of the Powerbook’s headphone output, by comparison, was congested and sloppy with looser bass and splashier top end. Tonally the Powerbook’s output was relatively neutral, but the sound through the Indigo, especially on vocals, was far more musical and involving.

     From a functional perspective the analog volume control is probably the Indigo’s standout feature. Listening at work often requires quick volume changes and stumbling around the cluttered keyboard or worse, having to use the mouse to hit some software button to bring down the level can be frustrating. Digital volume changes via software can often be delayed, especially if the computer has multiple programs running or is performing a processor-intensive task. A quick twist of the thumb is all that’s required to mute the Indigo no matter how busy or slow your computer may be. It also allows for finer volume adjustments, which is a nice change from many coarse PC interfaces which sometimes cause drastic jumps between adjacent volume settings. There’s even a software console application with basic mixer functions, allowing you to pan the output signal left and right as well as control output level.

     The Indigo is a fabulous way to turn a laptop into a high quality audio source, and, as such, it’s indispensable to someone like me. A digital output would be nice, allowing me to use the Powerbook with my D to A converter at home, but it otherwise does exactly what I need it to. If you use your laptop for listening to tunes at work, or watching movies on planes, or even playing games, you might just find the Indigo indispensable too.

Aaron Marshall