He is testing is the effect of using any kernel extension for routing audio. That is the function of DPSReflector and Soundflower. So, we are not seeing an issue with the DPS application (which does the processing) but with the internal routing of audio within Mavericks.
So when DPS is loaded (on or off) the DPSReflector is routing audio at the kernel extension level. When DPS is not running, Core Audio is handling sound using only its own internal mechanisms.
It seems Mavericks has issues with any audio kernel extension but there are no errors or documentation yet regarding this or changes to Core Audio for OSX. So we have to wait… :-/