Honestly, I did not perceive any remarkable signature difference when I went from the clip zip to the x3. I found it to be a little warmer and I did appreciate the functionality of the device.
But when I went to the dx50, there was an appreciable improvement in the signature going from the clip. The only time I had heard my iems sound so good was with the Asgard 2 and uberfrost. So after that experience, I stopped following the fiio products TBH.