The speakers on a given line can't be lower than 4 ohms. There are two right lines and two left lines. You could hook two 8 ohm speakers to each line in parallel and that would be 4 ohms per line. Plus from line one to plus on speaker one and speaker one plus to speaker two plus. Negative from line one to speaker one negative and speaker one negative to speaker two negative. If your speakers are 6 or 4 ohms you will underload the amp and blow the finals If you run in series two per line 4 ohms becomes 8 ohms but they are out of phase and might sound lousy as you just made an eight speaker noise cancelling system