To help you better understand what DACs do and why they are so important, we should define a few technical terms before we go into more detail. Basically, digital audio refers to sound information that has been recorded or transformed into a digital format. Digital sound waves are always encoded as discrete, sequential numerical samples that are invisible to the human eye. Digital audio can also be edited, copied, and changed in a variety of ways. You can do this as often as you like. However, as it stands, you can't really use it. Analog audio, on the other hand, is very different in that it cannot be edited or changed once it has been recorded. On the other hand, the only method for recording and reproducing sound in the past was analog audio. Its primary drawback was that it couldn't be changed, but its biggest advantage is that it's simpler to use (or at least, it was easier to work with). Analog and digital sound waves can best be understood by comparing them to the original sound waves to which they are related. In that regard, analog sound waves are exact replicas of what the original audio "looked" like; they are identical to the original. There isn't even the slightest difference between the graph of analog waves and the original sound waves. Essentially a binary representation of the analog recording, and digital sound waves. DACs, pre-amps, and amps use them to "refine" them into audible audio. Compared to a graph of analog sound waves, a graph of digital sound waves is "pointy" and "edgy." As previously mentioned, digital audio can be altered, just like a digital representation of digital sound waves. Graphs are represented differently by different programs.