Ever since I hooked up an external amp to my Receiver, I'm lacking any real bass control for 2 channel music. The external controls for bass management work fine, however, setting my speakers to Large or small makes NO difference whatsoever. Also, I used to have my sub set at about 35% when in 2 channel listening, and now to get that same amout of bass, I have to set it at about 80%. 1) I've tried setting all speakers to small. 2) I called Yamaha support and was told to set the "time level setting of the sub to Zero" which it was already set to. Basically, I've messed with every known setting on the receiver and CANNOT get good sub response from my sub except for Home Theater. I've very happy with Home Theater, but 2 channel music is driving me crazy! Shouldn't setting my speakers to large or small make any difference in sound?