Burr Brown is a company that manufacturers IC's and other electronic devices (such as DAC's).
24-bit is the resolution of the DAC. It just tells you a little bit (no pun intended //content.invisioncic.com/y282845/emoticons/tongue.gif.6130eb82179565f6db8d26d6001dcd24.gif ) about how the DAC goes about converting the digital signal to an analog signal.
Really; It's all overhyped.
Burr Brown is a good company that makes solid products. But having a "Burr Brown" DAC (or opamp, or anything else for that matter) doesn't automatically make it "sound better". And being 24-bit won't automatically "sound better" either.
For one; Burr Brown makes some 24-bit DAC's that are cheap enough that literally any product, even low-end Jensen type products, could use them. Secondly a DAC is only as good as it's supporting design.....a good DAC implemented into a poor design will have poor performance regardless of brand name or bit resolution. And even then they all have their advantages and disadvantages. There's no "perfect" way to do things.
In short; I'd never choose product A over product B based solely on product A having a 24-bit Burr Brown DAC and product B utilizing a different brand's 1-bit DAC.