I've been playing between delays of 0 to 40 on my TV and to be honest not sure which one is right as they all feel not 100% accurate in some way. Is there any bullet proof way to set this right? A specific video/sound material that will help do this.
I currently based myself on dialogs of movies and how lips of characters are moving according to what they say. Might not be the best way.
A tennis match is a good way to sync indeed.
You could film your screen in slowmotion with your smartphone to check if your delay is accurate.
Devialet 200 (FW 7.1.3) / Magnepan 1.7i / Rel T5 / Foobar (WASAPI event 24bit) / AIR 3.0.4 (Ethernet)
There are test clips to download to test this sort of thing.
Are you delaying the sound or the picture?
Air 3, Rega P9 with Dynavector XX2Mk2 > 440 Pro > Sonus Faber Guarneri Evolution
Not sure if anyone else has experienced this, but I notice the audio delay can fluctuate, so a hardset delay setting doesn't always work. For me at least, I need to adjust this delay once in a while, most-likely (I guess) due to network performance at that time. I use VLC player so that is quick with keyboard shortcuts.