What's your subjective opinion of the YPAO mode? Do you hear much difference in noise and distortion over Pure Direct mode? Does the proper bass crossover make up for it?
If you are still interested I am now able to give a meaningful reply.
Although I've had my bedroom setup for quite a while I hadn't set it up properly. But after much messing around I now have the sub placed where it gves some decent output, though quite a few feet away from where it 'fits' best. Plus my Amazon Music HD sub expires soon and I have been comparing it against a free trial of Qobuz to see which to keep. I used the 802 setup for that so have also been comparing the various modes, Pure Direct, Ypao and normal.
Firstly, here are some sample graphs -
Shown spaced out for comparison, these are left/right speaker pairs, for Pure Direct, Normal and YPAO, as annotated in the chart. I have not shown a graph for the subwoofer alone, but it has a fairly smooth slope downwards to 90Hz, then rolls off rapidly at 24dB/octave.
The top two show left and right Pure Direct, and you may notice dips at 75/80 Hz. I think this is where the Kef LS50 Metas are slightly out of phase with the subwoofer. Subwoofers tend to take a few milliseconds longer to put out the signal than plain speakers do, so the sound arrives late. That's an advantage of YPAO, it delays the signal to main speakers until the sub has caught up. The Kef KC62 sub, although it has excellent drivers (for their small size) also has poor electronics - instead of a continuously variable phase control it only has 0 and 180 degree options. I tried the 180 degree phase change, but, instead of a dip, gave a huge peak instead.
The LS50s output falls off below 100Hz. I think that if you used speakers with more extended bass then that could cause more problems. Though it would help if the sub had a good phase control, or you used something on the sub like a MiniDSP 2x4 HD with phase control built in.
The graphs at the bottom show the YPAO output. And I'm very surprised at how good they are. Cleaned up the area between 80-500Hz quite nicely I think.
Unlike Yamaha multichannel AVRs there's no choice of YPAO high frequency slopes, or manual adjustment. So it's a good job I generally like 'flat'. And there are tone controls. But how different sounding are the Pure Direct, standard and YPAO ? Well, if I were in a double-blind test I'd probably fail to tell them apart. There are slight differences, but I'm not sure if the differences are better or worse. In fact, if I apply the 'psychoacoustic' smoothing to the graphs above they all look pretty good.
Reckon I'd make a really rubbish subjective hifi reviewer for the magazines or YouTube. Manufacturers wouldn't send me any free stuff to review.
p.s. I chose to go with Qobuz and cancel my Amazon sub. No difference I could spot in quality but prefer the web app and recommendations of Qobuz. Plus, although I buy loads from them, I hate Amazon.