Hi. I have a littman s.e II but I can't hear out of it that well with heavier set people. I've tried it on my grandmother and I have a hard time. If I do get into the SON for this fall, I was wondering if I should invest in a new scope? I want to be able to hear well. I was taught to use my scope by a nurse.. And it works fine on most people. Thanks for any advice! Oh, and if I do get a new one.. Should I get the master cardiology or cardiology III?