I'm currently using a TDA 1545A based DAC that I'm pretty happy with. However, due to its limited inputs, I'm considering moving up. The DAC I'm considering uses the Burr Brown 24bit/192kHz chipset. Unfortunately, I'm going to have to buy it online and will not be able to audition. I realize that the TDA could be considered a bit long in the tooth but is the Burr Brown a definite step up? I'm planning to use it with my NAD cdp and to stream iTunes (AACs) via Airport Express.