See 1:55 time code in this YT video Eversolo DMP A6 VS Eversolo Z8 - Which Should You Buy? - YouTube I don't seem to have this VU meter option and the iOS app says my Z8 firmware is up to date?
The video is a comparison between the DMP-A6 and the DAC-Z8, so you may be referring to the VUs of the DMP-A6, which are more than those of the Z6/Z8. The Z8 has only four. e.g. the bueish, circle-ish ones are to be seen only on the A6. It could be nice if Eversolo made an update to the Z8 with those VUs added, though.