Symmetric Output for USB AudioDAC

This simple adapter circuit is specially intended for use with the USB Audio DAC published in the December 2000 issue of Elektor Electronics. With an easily implemented modification, it is possible to make the output of the D/A converter pseudo-symmetric, so that it can be connected to professional equipment having XLR line inputs. This will do even more justice to the high quality of the USB Audio DAC.The modification actually amounts to just adding a single resistor (R11a) and changing the value of the existing resistor at the output of the audio DAC (R11) from 100 ? to 68 ?.