Hello, I am looking to add an extension cab to my combo amp. I have never had more than a combo by itself. Right now I have an Eden Nemesis N15S. It is 120 watts at 8 ohms. I am going to be playing with a very loud drummer. If I add an 8 ohm cab, I'll have 170 watts at 4 ohms. I am wondering if I should add another 15 under the combo, or set a 2x10 on top of it. Any advise would be helpful. buying a new rig is not an option at this point. Thanks!