The D1 digital-to-analog converter from Audioengine is a standout value, as it offers great sound quality at a price that is more affordable than comparable units. This USB DAC is plug-and-play with Mac or PC, making it one of the easiest ways to bring your FLAC and Apple Lossless files to life. The sturdy metal casing with rubber front and rear plate has a compact footprint and a simple interface, with only a volume knob, power button, and a headphone jack on the front. On the back, there is one USB and one optical S/PDIF input, plus an RCA output. The front 3.5mm headphone port is your output option for headphone listening. A 1/4 inch jack would have been a nice addition as they more commonly need amplification, but the 3.5mm jack will be appreciated by those who are using budget headphones, since this is a budget unit in itself. The D1’s low 10 ohm output impedance will not work with some high impedance headphones (300 ohms or more), but when the impedances match up, the amplifier is excellent. For USB audio the D1 goes up to a 24-bit resolution and a sample rate of 96 kHz, which are standard specs for a DAC that aims for smooth and accurate conversion of data to sound. These two figures are commonly measured with a dual rating, in this case 24/96. This rating puts the audio fidelity of the D1 at the level of HD Blu-Ray audio. The D1 is characteristically low in jitter, and also has a high signal-to-noise ratio of 110dB makes for a clean sound with minimal digital distortion. The sonic accuracy of music played through the D1 is tighter, offering more room for individual frequencies to flourish, plus a wider sound stage. The frequency response of 10Hz – 25KHz also contributes to the added depth of the sound, and although it takes a trained ear to pick up this added complexity, it will immediately shine on that one song you’ve heard for the thousandth time. While I have no direct complaints about the sound, I am left feeling like something is missing from the audio experience of the D1. True individuals frequencies will stand out under the D1’s subtle influence, but after comparing to slightly pricier DACs, it is apparent that this system could perform even better. Such begins the slippery slope of audiophile gear. If reading about the D1 already has you thinking about an upgrade, the Audioengine D2 offers wireless streaming, and slight improvements on signal to noise ratio and frequency range for about double the price. But the vast world of potential improvements aside, the D1 is where the value is, as the unit’s solid amplification and compact footprint make it a great starting point for budding audiophiles.