Corsair Gaming RGB Keyboards
NCIX: http://bit.ly/1ms0EVl
Amazon: http://geni.us/1r6c
Earlier this month Linus and Luke were given an opportunity of a lifetime - to go to Germany and tour the Cherry MX factory. Of course they jumped on it, and they spent a pretty amazing day learning about Cherry and their practices...
A "DAC" is a digital-to-analog converter. It translates the digital signal made up of 1s and 0s to a continuous (analog) signal. A DAC only ouputs at line level and must be used with an amp in order to achieve a usable listening volume.
Likewise, you can't use an amp without a DAC if you're listening to a digital source (which most are these days). An amp may be paired with a DAC or not, but there is still a DAC somewhere in the signal chain, usually as a built-in audio processor such as on a motherboard.
Realistically, there isn't a huge difference between DAC chips (certainly not size). The most important thing is how the chip is implemented, but the music, then headphones, then amp, have the biggest impact on sound quality and signature.