No unfortunately it is not lossless.
This was discussed before in this thread → Request for DSD256 playback - #48 by Anupc
And to quote again folks who write software/firmware for the conversion;
Unlike conversions within the PCM format ( WAV to FLAC, etc ), conversions from DSD to PCM - or the other way round - cannot be done losslessly. This is a mathematical fact, even though some otherwise well-informed individuals can be heard to assert otherwise.