Error: When connecting to DAC volume goes to max (iPad)

[user-removed]

For not apparent reason when I connect Spotify from the Devices menu with my external DAC for music playback (Hegel 160 amp) Spotify changes the iPad volume to its maximum setting! The volume limit on my iPad settings doesn't seem to work either.  I have contacted also the manufacturer of the DAC as to address this issue.

Besides scaring my neighbours I'm afraid of damanging my hi-fi speakers if I continue using Spotify Premium. Anyone here with the same issue on a DAC of another brand?