Frantz,
I will not speak about the changes due to fuses, as I have not any experience about them. However IMHO the argument you present about audibility is very weak.
My own system is all ARC, but recently I am using a Dartzeel NH108/NH18s system with a Nagra CDP Cd player as a source. Just for fun I measured the acoustic frequency response using the two systems - it is similar withing .5 dB. The Dartzeel amplifier has an output impedance of .3 ohm, the damping factor is not very different from the ARC REF150. As both systems are currently assembled I can change from one to the other in five minutes, keeping both warmed up. One think is sure - the sound of the two systems is completely different along all the spectrum.
As I have been looking for a better position for the Aida's they have now Teflon pads and can be moved easily in my room. Moving them 3 feet and the listening position of the same amount, to keep the speaker to listener constant, can introduce changes up to 8 dB in the measured spectrum (1/6 octave weighting) but the perceived global audible differences are much smaller that the differences between the two different systems. The sonic signatures of the electronic systems, both measuring excellently , are IMHO larger than the effect of just moving the speakers.
Surely I am picking between two acceptable good sounding positions for the speakers, avoiding the so called bad positions.