In my continuing series of "Dumb questions Greg posts to MEF" I pose the following: Just obtained a vintage speaker/cab and it makes a somewhat unrefined tube amp sound amazeballs. No speaker indentifier that I've found, but pretty sure it is a Jensen P15L, LL, or maybe a P15N reconed to 16 ohm. I believe those are 40-50 watt speakers. The head is 120 watts. I can switch it to triode to keep the power down to 60 (still sounds fantastic) and so far I've been keeping the volume pretty low but it would be nice to know that I was putting out less than 40 watts. Actually would prefer even lower since clipped waves will probably be worse than clean signals.

I already have a 35 watt 16 ohm resistor wired up as a dummy load that I use for repair work. Amp has parallel jacks and switchable OT so can set it to 8 ohm.
Just wondering if there is anything *especially* dumb about putting a single power resistor in parallel with a speaker. Presumably some of the resistive attenuator boxes end up presenting a mix of resistive and reactive load to the output transformer, but don't want to make a dumb assumption.

Amp has auto biasing (Bugera Infinium), don't know if I can pull two tubes to cut the power and not have it freak out and turn into a flaming mess.

Thanks in advance,
Greg