A DAC is a Digital-to-Analog Converter. It turns 0s and 1s on a digital file such as that on a DVD or CD, usually in the form of Pulse Code Modulation, into an analog electrical signal that our audio electronics can understand and amplify so that our speakers make sounds. As you might imagine, an ADC turns analog signals into digital signals, which is important for recording. Processors/receivers often have both ADCs and DACs in their circuitry in order to do many different audio related things.
Once controls of things like volume and cost are set into place, people fail to distinguish between DACs in listening tests. basically, most good modern DACs are so similar that you won't likely be able to tell the difference. Early in the days of digital I bet there were some poor DACs out there that messed up the signal during the conversion, but we're not in the 1980s now are we?
Burr-Brown is a brand name of Texas Instruments which makes good DACs.
So does Cirrus Logic, Analog Devices, Wolfson, etc.
All brands make different, quality DACs which, when well-implemented work well. They work so well that we can't tell the difference.
Therefore having a burr-brown DAC doesn't mean much. Some people believe they can hear the difference between DACs (even if they can't, they think they can) so they like to buy things based on the brand of DAC. So it's purely marketing.
FWIW If I was picking a DAC it would probably be the wolfson ones. lol.