Hello ! I bought a pretty cheap TRRS 4 pole cable to try out the balanced DACs. I connected the Onkyo to balanced Oppo PM3 headphones. I get a bad hugely phased mono signal in BTL (balanced) mode. But it strangely seems to work in ACG mode... I made a pink noise alternating from left to right for further testing: my balanced mode seems to mix channels in a weird way. I wonder if the cable is well connected to all pins inside the jack of the headphones. I strongly doubt there is a problem here. I also wonder if the cable is not wired in a strange way for cellphones microphones etc. I strongly doubt that too because there are 4 pins on both sides of the cable. Knowing it seems to work in ACG mode, what else could it be ? Maybe the problem is also present for ACG mode and I only hear its specific ground effect giving me the impression it is working. As you can see, I still have not understood the true difference between BTL and ACG. Even before hearing it. Thanks !