I have an EL84 based amp with 4 x EL84 power tubes. I also have a schemtic for it. The amp is a 40W amp, but the schematic shows an option for 20W which only involves removing two of the EL84's and changing a resistor value from 51R to 100R. What I'd like to know is if I can just remove the two EL84s and run at 20W without changing the 51R, and would that hurt the amp, or seriously shorten the life of the tubes. I have the portion of the schematic in question shown at www.codekinesis.com/files/el84.tif which shows half of the power amp section (the other half is symmetrical to what's pictured, and the 51R applies to all 4 power tubes). (I don't know if I'm showing enough of the schematic to evaluate, so let me know if you need more info.) I can modify the amp to switch from 51R to 100R no problem, but just wondering if I can "cheat" and avoid the mod.