I have a Bogner Atma. 4, 8 or 16 ohms. I have a 2X12 cabinet with 8 ohm speakers. So I run it at 4 ohms. Positive terminal to positive terminal. Sounds great. So then I wired the speakers to run it at 8 ohms. I wired the speakers negative to positive to make the two 8 ohms speakers be at 8 ohms. Sounded too trebly. Is that normal?