1.How large should the speakers be to set them to "large"? 2.When i do set them to "large" the bass from LFE(.1) is also played by the "large" speakers.Also they work like sub to play other channel bass. How do I make the sub alone play LFE and leave the fronts for it's own bass? 3.The crossover is at 150Hz.How can I change it? Model : Sony HT-SL5.