Hi everyone ,this is my first post. There has been many questions reguarding extension cabs and correct speaker ohms. I spoke to peavey tech,to clarify this. It is safe to use 8 or 16ohm load. You may damage your amp if you use 2 or 4ohm. To get full power, and the best tone 8ohm is the best choice. I put 2 cabs side by side,one at 8ohm, and the other at 16ohms. Huge diffirence,more power and much better overall sound. Ill never run 16ohm with this amp again. Sorry for rambeling. Hope this helps even one player, Thanks for reading,codyboy