Unless I'm really missing something the only sub choices I've seen so far is "none, L/R + Sub or LFE only" regardless if my mains are set to large or small. It appears I have to turn the sub on before I can set the mains to small, at that time I only have the three choices noted above. However, I don't believe I've gone back to the sub menu after setting the mains to small, perhaps that's when the on/off (yes/no) choices appear.

Thanks!