What the hell are ohms? I know that they are a unit of measurement, but what does it all mean Basil? <- Austin Powers. What's the difference between 4 ohms and 8 ohms (besides 4 ohms). What happens if you have two cabs, one that takes 400 watts at 8 ohms and one that takes 400 watts at 4 ohms powered by a head that puts out 350 watts at 4 ohms or 240 watts at 8 ohms. For clarification, I'm talking about a Hartke 4.5XL cab, 215B cab and a 7000 head. Thanx for the help.