underfelt under vinyl?

[DIYspanner]

Planning to put vinyl on the floor in small WC but want to make it a soft floor so I figured if I laid carpet under felt on the wood floor then the vinyl, it would be adequate.

Any expert vinyl layers see any issue with this arrangement?

 

[footprints]

Not a good idea the vinyl will flex and move as you walk on it. Paper felt is OK for helping to cover slight imperfections but will make very little improvement to the vinyl best to go for the thickest one you can get, some are very thin.