We live in an analog world. The D/A converter or "DAC" is the essential bridge between digital storage and analog playback. Today, virtually every audio device has a built-in DAC. CD players, DVD players, computers, HDTVs, cable boxes, even smartphones, all have built-in D/A converters.
The entire audio system in a consumer audio device is normally built for a budget of about $5. At this price, the results fall well short of high-resolution audio performance. These internal converters may boast that they support 24-bits and 192 kHz, but In most cases, they cannot even do justice to the CD format. Internal converters typically provide the equivalent of 14-bit performance. The remaining 10 bits serve marketing purposes.
Fortunately, most audio products now have digital outputs. These outputs bypass the internal converters and deliver raw uncorrupted digital data, losslessly preserving all of the details captured in the recording. These digital outputs can be connected to an outboard D/A converter. This connection effectively replaces the low-quality internal converter with a high-quality outboard converter. The performance improvement is often huge.
Any practical audio system will need a volume control. These days, most audio devices use digital volume controls. These controls place significant additional demands on the quality of the D/A conversion. An internal D/A converter that starts with the equivalent of 14-bit performance, may only deliver 12-bit performance at typical volume-control settings. In contrast, the Benchmark DAC2 D/A converter delivers true high-resolution audio performance over a wide range of volume settings.