someone recommended using a 100 watt resistor instead of my speaker cab when I bias my amp. I've got a Marshall jcm 800. I bought a 100 watt 15 ohm resistor. (big ceramic tube). Since this is 15 ohm instead of 16 (they didnt make 16 ohm) will this negatively affect my current or plate voltages? I dont think so but thought I'd better check. I assume I can just take a speaker cable, put a 1/4 jack on one end and solder the resistor to the other end of the cable and plug that into the amps speaker output. Correct? I'm also assuming through this whole thing that you DO in fact need SOMETHING plugged into your speaker output when you bias.