Since this morning, I have had an echo between my ND5XS2 and QB2 speakers while streaming Tidal. I have tried the Naim app and McConnect. This problem does not occur when listening to radio. Does anyone know what the problem could be? The ND5XS2 has an Ethernet connection, the QB2 are connected via wifi. I have not had this problem before.
The problem seems solved!
Magick… 
turned it Off and ON again?
Switched between the Naim and McConnect apps and between Tidal and radio. Not sure how the echo appeared and how it disappeared … I’m glad it works again!