Tone and soundstage are two very separate performance characteristics IME.
The academic studies of psychoacoustics better explains the difference your friend claims to hear - more so than any quasi-technical explanations you’ll find littered throughout the web and this forum.
The only ways a power cord might affect the sound is if it either, a) restricts current (increases resistance) to the point that it limits the amplifier beyond its maximum current draw capability, or b) its shielding is different, thereby causing an increase or decrease in the total EMI of the system. These two scenarios are both uncommon.
What is most likely is that your friend expected to hear a difference which affected his/her brain chemistry (altered mood) which led to a real perception (not necessarily reality) of difference. That’s about as close as a component can get to creating "magic." Remember that all magic is an illusion.
The same phenomenon occurs when one listens to their system while fatigued, or following a stressful day.
The academic studies of psychoacoustics better explains the difference your friend claims to hear - more so than any quasi-technical explanations you’ll find littered throughout the web and this forum.
The only ways a power cord might affect the sound is if it either, a) restricts current (increases resistance) to the point that it limits the amplifier beyond its maximum current draw capability, or b) its shielding is different, thereby causing an increase or decrease in the total EMI of the system. These two scenarios are both uncommon.
What is most likely is that your friend expected to hear a difference which affected his/her brain chemistry (altered mood) which led to a real perception (not necessarily reality) of difference. That’s about as close as a component can get to creating "magic." Remember that all magic is an illusion.
The same phenomenon occurs when one listens to their system while fatigued, or following a stressful day.