Break your power supply challenge

[Pim]

When I switched on the air conditioner in another room, I can hear a slight dip in soundstage a few seconds later.

I had a go at trying to replicate this last night. I used Joe Bonamassa's Athens to Athens on the An Acoustic Evening album. It's one of those songs that can give a sound stage that's wider than the speakers, by about a meter to the left and 0.8m to the right. It's easy to pin point where the instruments are and it's repeated / long term. 

I was using the air conditioner in our living / listening room so I didn't want the fan to be on. To achieve this I turned it to heating; this way it does a few minutes of 'prep work' on the outside unit before it starts the fan. I also pre-heated two ovens (fans off) to pull away even more power from the amps.

I couldn't hear any change in sound stage but I did have a feeling there was some difference in how the instruments sounded at first (Strings seemed to sound more accurately like strings) I repeated the test and found I couldn't hear that difference again.