I did a week of regular use with the z1 and noticed improvement along the days. I think 100 hours is a safe bet.
The word Zishan means "yew" according to google translate. I assume this means Chinese yew? It's a nice looking small tree. http://www.treetopics.com/taxus_chinensis/chinese_yew_1250855.png
Couple things I noticed...unlike the Walnut, if you remove the card, the Z1 does not remember where you left off and it starts from the beginning of your card. It remembers where you left off if you merely shut it off without removing the card. Also there is a slight cut off of songs when skipping forward through songs. I believe it is when it skips from one folder to another, so better to use less folders (however you want to organize them on your card).
Given my limited understanding of Chinese I ponder it may also mean 'hair dryer', 'large pile of beans' and 'look, there is an ufo behind the clouds' depending on context.
Yes, I tried the Z1 as DAC on my Mac and it worked flawlessly as well. Conversely, I tried to use the Shanling M1 as a transport with the Z1 as the DAC output but the Shanling kept getting errors stating that each file was "not supported" except....24/48 FLAC files. I thought that was weird. All my files were FLAC 16/44, 24/96, 24/192, and 24/48.
The Zishan Z1 is smaller, lighter and sounds better than the Walnut v2.1? That's sad to hear for Walnut owners like myself.