I'm logging my experience with a Z9 Mini and tracking the overheads versus revenues:

 - 44% of breakeven reached after 58 days (& 1/3 of the hash power).
 - DIY silencer works surprisingly well.

https://steemit.com/mining/@unfairfunfair/mining-zcash-with-the-antminer-z9-mini-part-5-progress-update-and-silencing