Originally Posted by MichaelJHuman
I have always preferred small. Whether that's the highest fidelity or not, I could not say. When my Yamaha YPAO set my bass to both, I especially did not care for it. That sounds schizoid.
I don't see any reason to have the "both" setting. And in the Audyssey thread the guy who designed that stuff always tells people to set speakers to small. There are other reasons that don't necessarily apply to every receiver, for example the sub channel often gets more accurate EQ than the others (because low bass requires high resolution filters), and you need all the low bass going to the sub to benefit from that.
Also room modes (standing waves) are easier to control when you can change the position of the single speaker (the sub) that's causing them. And the Yamaha Z11 has a special standing wave correction PEQ that only applies to the sub channel, so even people with powered subs in their mains would benefit from setting those speakers to small.
But the good thing about the Yamaha system memories is you can easily compare several different setups and see which you prefer. Each room behaves differently.