I just learned that my speakers are 4 ohms for most of the lower frequencies, but I have been running in the 8 ohm output of my Willsenton R8 amp, as the speakers are labeled 8 ohm. The center power transformer ran very warm with the speakers plugged into the 8 ohm speaker outputs.

Last night I tried using the 4 ohm outputs, the result was all 3 transformers were cool to the touch, slight warmth on center power, but nothing like before.

I think I saw a video explaining that running lower impedance speakers than the output rating would overheat the output transformers. But in mine it was trying to overheat my power supply transformer.

I guess the heat is coming from that for a given voltage amplification, it is putting out essentially twice the current. Thus the power transformer was getting hot.

Is that right? Would there be negative effects of pulling too much current through the output tubes?

Was the amp putting out over rated power? But not clipping because there was still voltage headroom to amplify more?

Just trying to understand why solid state amps are built with bigger power supplies to handle lower impedance loads, but tube amplifiers are given different output transformer windings.