Send audio file to ethernet port of DLNA AV Receiver

Downloaded a 5.1 Surround 24BIT/96kHz FLAC…Plays stuttering
Also played a 24bit/96kHz flac…no stuttering.

But I also noticed volume differences:

Spotify via Airplay = Loudest!
DLNA streaming from my NAS =Louderer
Playing files from NAS storage added to Volumios library = Less Loud (24bit/96kHz flac)

Any idea why they all have different volume output?

There is no support for multi channel sound on the current HDMI driver, only stereo.
I have no idea on why there are differences on output levels? You should play the same music file through different transport mechanism (airplay, DLNA, etc…) to evaluate the differences on sound levels.