These full range measurements are not helpful for setting the Distances. You need to run the speakers and subs *together* in order to check the blend of their outputs at the crossover. The Distance setting is actually a "timing" setting. The Bass Management system looks at the Distances and uses them to set delays. For example, if the sub is the furthest away, it will "fire" first, and the speakers will be delayed relative to the sub. The goal is to have all the waves from all the speakers and sub(s) arrive at the LP at the same *TIME*.
Why is this important? If the waves arrive at different times, then the waves will be out of phase. If the negative side of one wave arrives at the same time as the positive side of another wave, they'll cancel each other and there will be no sound. I showed a graph of this phenomenon on the previous page. Here it is again:
The blue trace shows the cancellation cause by the out of phase arrival of the waves from the subs and the waves from the speakers. The green trace has had the subwoofer Distance adjusted so the delays are correct and both waves arrive in-phase with each other. The cancellation is gone.
The crossover in these traces is 80 Hz. The cancellation happens because both the speakers and the subs are generating 80 Hz. Above 80 Hz only the speakers are generating sound, while below 80 Hz only the subs are generating sound. The crossover filters are not hard "brick walls", but instead they have slopes. You can see the slopes in the response a little above and a little below 80 Hz.
Here is another system where the subwoofer Distance setting was much better to start with. Still, with some adjustment, I was able to get another 5 dB around the crossover frequency:
Above I suggested some steps to optimize your system. Two of the steps were:
When YPAO is done, set the crossovers for your speakers to 80 Hz for your mains and to whatever is optimal for your surrounds, (you don't list surrounds, so I don't know what they are.)
Measure the response with XTZ, being especially aware of the response at 80 Hz. Adjust the subwoofer Distance setting to optimize the response around the 80 Hz crossover point.
When I suggested measuring the response with XTZ, I meant to use the Room Analyzer screen to check the response around the crossover. YPAO will have set the Distances, including the subwoofer Distance. Use that as the starting point. Then try adding some distance to the subwoofer and see if the response improves. If it does, add a little more, continuing until you get the highest response at the crossover frequency. If you can't get it all the way up to "flat", you can then try using some boost in the DD software, but you should always try to get as close to flat first before adding any boost.
Here's a question: When you run YPAO with the subs set to "Stereo", does YPAO chirp the subs separately, or together? Or, does it chirp the subs separately... and then also chirp them together?