I have done things like that in a pinch. Of course, it will NOT pass anybody's QC inspection!
50mV of ripple on the output of a switching supply isn't anything to brag about, but it's not unusual. Does your supply have a published specification for ripple?
However, the audible whine sounds like the supply may be overloaded, or possibly underloaded. Have you calculated your circuit's current draw, and verified that it's within the supply's capability?
p.s. - Or maybe you simply have sensitive ears. Are you a 13-year old girl? I think they are supposed to have the best hearing of all people.