Single vs Dual Power Transformers

If a single power transformer is used, are separate secondary windings for each channel used in all stereo amplifiers or is this configuration in the dual mono or partially dual mono camp? I'm just trying to understand why some manufacturers hype separate secondary windings as complete power supply separation for each channel, despite a solitary power transformer.

It is better to have dual windings than to have both channels share the same supply. The weakness of this approach is that the two supplies still can 'talk' to each other through the core and primary winding of the transformer, although certainly there will be less noise than if the two channels shared the same supply. IOW this is a step to better performance; better yet would be dual power transformers.

There are a lot of variables at play here so nothing can be considered case in concrete; I am merely stating how this works strictly from the point of view of power transformers. There can be other considerations in a design that may negate this issue- ultimately audition is the best course of action.

Thank you again, Atmasphere, for your complete and well explained answer. Given other considerations in design being well implemented, monoblock amplifiers and stereo units with dual power transformers should
lead to less IMD and possibly better sound. And yes, audition is a must, as "better" is quite variable amongst audiophiles.

I can say this, I would take my Vitus SIA-025 (which has a single transformer with separate windings for the left & right channels, then is dual mono after that) over a Simaudio Moon Evo 700i (which has separate transformers). Always the sound is most important.

I was told that one negative to dual mono transformers is if there happens to be a time when the recording requires an unbalanced surge of power to the left or right channel in which one of the two smaller transformers might not be able to provide all the power to that channel that a single larger transformer can provide.