Starting with Audirvana Plus release 2.5.1
This is the ultimate step in upsampling to send to the DAC the closest signal to the one used internally in its DAC chip immediately before the conversion to analog. This enables, with native DSD compatible DACs, to bypass all digital filters and processing done in the DAC chip by those done by Audirvana Plus.
The Mac computer CPU is much more powerful than the DAC chip and thus enables to use much more sophisticated upsampling algorithms to give strongly increased sound quality.
Please note that some very loud tracks have hard clipping. This can create trouble with the sigma-delta modulator that leads to one second of silence on one channel. If this happens, can you first try to set a lower value for the « Safe volume reduction before DSD upsampling » like -3dB? This should help as this rare issue is more likely to happen with very loud tracks.
Enjoy the new great improvement in sound quality!
With a DSD compatible DAC, there a new Forced upsampling option in the Audio Filters page of the preferences.
You can tune the output both the iZotope advanced filter settings, and the type of DSD filter.