Teac UD-501 USB DAC

The UD-501 is a dedicated Digital-to-Analogue converter designed to process digital signals from a variety of sources, including PCs/Macs, and then output them as analogue signals to an amplifier such as the AI-501DA.
 
Internally, it employs two 32-bit/192kHz BurrBrown PCM1795 DAC chips (one for each of the stereo channels) with four audiophile-grade MUSES8920 OpAmps (a pair per channel) delivering the analogue output. That output stage is also buffered to ensure a linear signal performance, Being a Dual Mono design there are separate toroidal transformers for each channel (which is why it weighs an incredible 4kg).
 
The UD-501 is capable of natively handling DSD over USB (2.8/5.6Mhz files) and PCM audio files of up to 32-bit/384kHz resolution, sourced both PCs and Macs, and offers a range of custom filtering options for both DSD and PCM files. What that means in English is that adventurous computer audio fans will get state of the art replay of pretty much any digital signal they care to feed it.
 
As you'd expect the impressive processing capabilities are partnered by a generous range of inputs: USB, 2 x optical, 2 coaxial, and both balanced (XLR) and unbalanced (RCA) outputs, as well as very high quality headphone stage.