(Airplay) Lip sync for AppleTV direct connection over Airplay

Hi everyone, I am new to Naim (Uniti Atom) and also to this forum. So, first, thanks for having me here and best wishes to all music lovers out there.

Since I had a problem at the very start which I couldn’t find an answer for, I would like to share my solution with you.

Starting point: I wanted to connect my AppleTv to my Atom via AirPlay 2 in order to have a direct connection without going through the TV (since the latest AppleTv does no longer have any other outputs than HDMI).

The problem is, that for this connection you need video and audio to be in sync which was not the case by default.

AppleTv give you the opportunity to solve this via a lip sync functionality, which would use the internal mic of an iPhone to help you through an automatic configuration process. This would be just fine IF the test tone was played through the Atom. BUT: the test tone did not come.

If someone had this problem before: here is my solution…

AppleTv can output to both TV (over HDMI) and Airplay speakers (here Atom) at the same time. I attached my Atom to the TV over optical out (ARC should be just fine as well). As the test tone wouldn’t come over Airplay only, it now DID come through the TV connection.
Of course it was now in sync.

Now, here is my trick: i added some delay in the Naim app for the digital input I was using for the TV. It came out that 12 ms was a good value. Because now, with that forced delay, I started the configuration wizard again and the test tone came “too late”. This was recognized by the AppleTv wizard and solved by the AppleTv. After that, I could reset the delay for the digital IN and be happy with an Airplay connection with perfect lip sync.

Best regards,
Rob